Merge tag 'drm-next-2026-04-15' of https://gitlab.freedesktop.org/drm/kernel

Pull drm updates from Dave Airlie:
 "Highlights:
   - new DRM RAS infrastructure using netlink
   - amdgpu: enable DC on CIK APUs, and more IP enablement, and more
     user queue work
   - xe: purgeable BO support, and new hw enablement
   - dma-buf : add revocable operations

  Full summary:

  mm:
   - two-pass MMU interval notifiers
   - add gpu active/reclaim per-node stat counters

  math:
   - provide __KERNEL_DIV_ROUND_CLOSEST() in UAPI
   - implement DIV_ROUND_CLOSEST() with __KERNEL_DIV_ROUND_CLOSEST()

  rust:
   - shared tag with driver-core: register macro and io infra
   - core: rework DMA coherent API
   - core: add interop::list to interop with C linked lists
   - core: add more num::Bounded operations
   - core: enable generic_arg_infer and add EMSGSIZE
   - workqueue: add ARef<T> support for work and delayed work
   - add GPU buddy allocator abstraction
   - add DRM shmem GEM helper abstraction
   - allow drm:::Device to dispatch work and delayed work items
     to driver private data
   - add dma_resv_lock helper and raw accessors

  core:
   - introduce DRM RAS infrastructure over netlink
   - add connector panel_type property
   - fourcc: add ARM interleaved 64k modifier
   - colorop: add destroy helper
   - suballoc: split into alloc and init helpers
   - mode: provide DRM_ARGB_GET*() macros for reading color components

  edid:
   - provide drm_output_color_Format

  dma-buf:
   - provide revoke mechanism for shared buffers
   - rename move_notify to invalidate_mappings
   - always enable move_notify
   - protect dma_fence_ops with RCU and improve locking
   - clean pages with helpers

  atomic:
   - allocate drm_private_state via callback
   - helper: use system_percpu_wq

  buddy:
   - make buddy allocator available to gpu level
   - add kernel-doc for buddy allocator
   - improve aligned allocation

  ttm:
   - fix fence signalling
   - improve tests and docs
   - improve handling of gfp_retry_mayfail
   - use per-node stat counters to track memory allocations
   - port pool to use list_lru
   - drop NUMA specific pools
   - make pool shrinker numa aware
   - track allocated pages per numa node

  coreboot:
   - cleanup coreboot framebuffer support

  sched:
   - fix race condition in drm_sched_fini

  pagemap:
   - enable THP support
   - pass pagemap_addr by reference

  gem-shmem:
   - Track page accessed/dirty status across mmap/vmap

  gpusvm:
   - reenable device to device migration
   - fix unbalanced unclock

  bridge:
   - anx7625: Support USB-C plus DT bindings
   - connector: Fix EDID detection
   - dw-hdmi-qp: Support Vendor-Specfic and SDP Infoframes; improve
     others
   - fsl-ldb: Fix visual artifacts plus related DT property
     'enable-termination-resistor'
   - imx8qxp-pixel-link: Improve bridge reference handling
   - lt9611: Support Port-B-only input plus DT bindings
   - tda998x: Support DRM_BRIDGE_ATTACH_NO_CONNECTOR; Clean up
   - Support TH1520 HDMI plus DT bindings
   - waveshare-dsi: Fix register and attach; Support 1..4 DSI lanes plus
     DT bindings
   - anx7625: Fix USB Type-C handling
   - cdns-mhdp8546-core: Handle HDCP state in bridge atomic_check
   - Support Lontium LT8713SX DP MST bridge plus DT bindings
   - analogix_dp: Use DP helpers for link training

  panel:
   - panel-jdi-lt070me05000: Use mipi-dsi multi functions
   - panel-edp: Support Add AUO B116XAT04.1 (HW: 1A); Support CMN
     N116BCL-EAK (C2); Support FriendlyELEC plus DT changes
   - panel-edp: Fix timings for BOE NV140WUM-N64
   - ilitek-ili9882t: Allow GPIO calls to sleep
   - jadard: Support TAIGUAN XTI05101-01A
   - lxd: Support LXD M9189A plus DT bindings
   - mantix: Fix pixel clock; Clean up
   - motorola: Support Motorola Atrix 4G and Droid X2 plus DT bindings
   - novatek: Support Novatek/Tianma NT37700F plus DT bindings
   - simple: Support EDT ET057023UDBA plus DT bindings; Support Powertip
     PH800480T032-ZHC19 plus DT bindings; Support Waveshare 13.3"
   - novatek-nt36672a: Use mipi_dsi_*_multi() functions
   - panel-edp: Support BOE NV153WUM-N42, CMN N153JCA-ELK, CSW
     MNF307QS3-2
   - support Himax HX83121A plus DT bindings
   - support JuTouch JT070TM041 plus DT bindings
   - support Samsung S6E8FC0 plus DT bindings
   - himax-hx83102c: support Samsung S6E8FC0 plus DT bindings; support
     backlight
   - ili9806e: support Rocktech RK050HR345-CT106A plus DT bindings
   - simple: support Tianma TM050RDH03 plus DT bindings

  amdgpu:
   - enable DC by default on CIK APUs
   - userq fence ioctl param size fixes
   - set panel_type to OLED for eDP
   - refactor DC i2c code
   - FAMS2 update
   - rework ttm handling to allow multiple engines
   - DC DCE 6.x cleanup
   - DC support for NUTMEG/TRAVIS DP bridge
   - DCN 4.2 support
   - GC12 idle power fix for compute
   - use struct drm_edid in non-DC code
   - enable NV12/P010 support on primary planes
   - support newer IP discovery tables
   - VCN/JPEG 5.0.2 support
   - GC/MES 12.1 updates
   - USERQ fixes
   - add DC idle state manager
   - eDP DSC seamless boot

  amdkfd:
   - GC 12.1 updates
   - non 4K page fixes

  xe:
   - basic Xe3p_LPG and NVL-P enabling patches
   - allow VM_BIND decompress support
   - add purgeable buffer object support
   - add xe_vm_get_property_ioctl
   - restrict multi-lrc to VCS/VECS engines
   - allow disabling VM overcommit in fault mode
   - dGPU memory optimizations
   - Workaround cleanups and simplification
   - Allow VFs VRAM quote changes using sysfs
   - convert GT stats to per-cpu counters
   - pagefault refactors
   - enable multi-queue on xe3p_xpc
   - disable DCC on PTL
   - make MMIO communication more robust
   - disable D3Cold for BMG on specific platforms
   - vfio: improve FLR sync for Xe VFIO

  i915/display:
   - C10/C20/LT PHY PLL divider verification
   - use trans push mechanism to generate PSR frame change on LNL+
   - refactor DP DSC slice config
   - VGA decode refactoring
   - refactor DPT, gen2-4 overlay, masked field register macro helpers
   - refactor stolen memory allocation decisions
   - prepare for UHBR DP tunnels
   - refactor LT PHY PLL to use DPLL framework
   - implement register polling/waiting in display code
   - add shared stepping header between i915 and display

  i915:
   - fix potential overflow of shmem scatterlist length

  nouveau:
   - provide Z cull info to userspace
   - initial GA100 support
   - shutdown on PCI device shutdown

  nova-core:
   - harden GSP command queue
   - add support for large RPCs
   - simplify GSP sequencer and message handling
   - refactor falcon firmware handling
   - convert to new register macro
   - conver to new DMA coherent API
   - use checked arithmetic
   - add debugfs support for gsp-rm log buffers
   - fix aux device registration for multi-GPU

  msm:
   - CI:
      - Uprev mesa
      - Restore CI jobs for Qualcomm APQ8016 and APQ8096 devices
   - Core:
      - Switched to of_get_available_child_by_name()
   - DPU:
      - Fixes for DSC panels
      - Fixed brownout because of the frequency / OPP mismatch
      - Quad pipe preparation (not enabled yet)
      - Switched to virtual planes by default
      - Dropped VBIF_NRT support
      - Added support for Eliza platform
      - Reworked alpha handling
      - Switched to correct CWB definitions on Eliza
      - Dropped dummy INTF_0 on MSM8953
      - Corrected INTFs related to DP-MST
   - DP:
      - Removed debug prints looking into PHY internals
   - DSI:
      - Fixes for DSC panels
      - RGB101010 support
      - Support for SC8280XP
      - Moved PHY bindings from display/ to phy/
   - GPU:
      - Preemption support for x2-85 and a840
      - IFPC support for a840
      - SKU detection support for x2-85 and a840
      - Expose AQE support (VK ray-pipeline)
      - Avoid locking in VM_BIND fence signaling path
      - Fix to avoid reclaim in GPU snapshot path
      - Disallow foreign mapping of _NO_SHARE BOs
   - HDMI:
      - Fixed infoframes programming
   - MDP5:
      - Dropped support for MSM8974v1
      - Dropped now unused code for MSM8974 v1 and SDM660 / MSM8998

  panthor:
   - add tracepoints for power and IRQs
   - fix fence handling
   - extend timestamp query with flags
   - support various sources for timestamp queries

  tyr:
   - fix names and model/versions

  rockchip:
   - vop2: use drm logging function
   - rk3576 displayport support
   - support CRTC background color

  atmel-hlcdc:
   - support sana5d65 LCD controller

  tilcdc:
   - use DT bindings schema
   - use managed DRM interfaces
   - support DRM_BRIDGE_ATTACH_NO_CONNECTOR

  verisilicon:
   - support DC8200 + DT bindings

  virtgpu:
   - support PRIME import with 3D enabled

  komeda:
   - fix integer overflow in AFBC checks

  mcde:
   - improve bridge handling

  gma500:
   - use drm client buffer for fbdev framebuffer

  amdxdna:
   - add sensors ioctls
   - provide NPU power estimate
   - support column utilization sensor
   - allow forcing DMA through IOMMU IOVA
   - support per-BO mem usage queries
   - refactor GEM implementation

  ivpu:
   - update boot API to v3.29.4
   - limit per-user number of doorbells/contexts
   - perform engine reset on TDR error

  loongson:
   - replace custom code with drm_gem_ttm_dumb_map_offset()

  imx:
   - support planes behind the primary plane
   - fix bus-format selection

  vkms:
   - support CRTC background color

  v3d:
   - improve handling of struct v3d_stats

  komeda:
   - support Arm China Linlon D6 plus DT bindings

  imagination:
   - improve power-off sequence
   - support context-reset notification from firmware

  mediatek:
   - mtk_dsi: enable hs clock during pre-enable
   - Remove all conflicting aperture devices during probe
   - Add support for mt8167 display blocks"

* tag 'drm-next-2026-04-15' of https://gitlab.freedesktop.org/drm/kernel: (1735 commits)
  drm/ttm/tests: Remove checks from ttm_pool_free_no_dma_alloc
  drm/ttm/tests: fix lru_count ASSERT
  drm/vram: remove DRM_VRAM_MM_FILE_OPERATIONS from docs
  drm/fb-helper: Fix a locking bug in an error path
  dma-fence: correct kernel-doc function parameter @flags
  ttm/pool: track allocated_pages per numa node.
  ttm/pool: make pool shrinker NUMA aware (v2)
  ttm/pool: drop numa specific pools
  ttm/pool: port to list_lru. (v2)
  drm/ttm: use gpu mm stats to track gpu memory allocations. (v4)
  mm: add gpu active/reclaim per-node stat counters (v2)
  gpu: nova-core: fix missing colon in SEC2 boot debug message
  gpu: nova-core: vbios: use from_le_bytes() for PCI ROM header parsing
  gpu: nova-core: bitfield: fix broken Default implementation
  gpu: nova-core: falcon: pad firmware DMA object size to required block alignment
  gpu: nova-core: gsp: fix undefined behavior in command queue code
  drm/shmem_helper: Make sure PMD entries get the writeable upgrade
  accel/ivpu: Trigger recovery on TDR with OS scheduling
  drm/msm: Use of_get_available_child_by_name()
  dt-bindings: display/msm: move DSI PHY bindings to phy/ subdir
  ...

1 files changed, 320 insertions, 121 deletions

diff --git a/drivers/gpu/nova-core/gsp/cmdq.rs b/drivers/gpu/nova-core/gsp/cmdq.rs
index c1fbc54d9a41..275da9b1ee0e 100644
--- a/drivers/gpu/nova-core/gsp/cmdq.rs
+++ b/drivers/gpu/nova-core/gsp/cmdq.rs
@@ -1,20 +1,27 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use core::{
-    cmp,
-    mem, //
-};
+mod continuation;
+
+use core::mem;
 
 use kernel::{
     device,
     dma::{
-        CoherentAllocation,
+        Coherent,
         DmaAddress, //
     },
     dma_write,
-    io::poll::read_poll_timeout,
+    io::{
+        poll::read_poll_timeout,
+        Io, //
+    },
+    new_mutex,
     prelude::*,
-    sync::aref::ARef,
+    ptr,
+    sync::{
+        aref::ARef,
+        Mutex, //
+    },
     time::Delta,
     transmute::{
         AsBytes,
@@ -22,6 +29,13 @@ use kernel::{
     },
 };
 
+use continuation::{
+    ContinuationRecord,
+    SplitState, //
+};
+
+use pin_init::pin_init_scope;
+
 use crate::{
     driver::Bar0,
     gsp::{
@@ -29,7 +43,8 @@ use crate::{
             GspMsgElement,
             MsgFunction,
             MsgqRxHeader,
-            MsgqTxHeader, //
+            MsgqTxHeader,
+            GSP_MSG_QUEUE_ELEMENT_SIZE_MAX, //
         },
         PteArray,
         GSP_PAGE_SHIFT,
@@ -40,10 +55,14 @@ use crate::{
     sbuffer::SBufferIter, //
 };
 
+/// Marker type representing the absence of a reply for a command. Commands using this as their
+/// reply type are sent using [`Cmdq::send_command_no_wait`].
+pub(crate) struct NoReply;
+
 /// Trait implemented by types representing a command to send to the GSP.
 ///
-/// The main purpose of this trait is to provide [`Cmdq::send_command`] with the information it
-/// needs to send a given command.
+/// The main purpose of this trait is to provide [`Cmdq`] with the information it needs to send
+/// a given command.
 ///
 /// [`CommandToGsp::init`] in particular is responsible for initializing the command directly
 /// into the space reserved for it in the command queue buffer.
@@ -58,6 +77,10 @@ pub(crate) trait CommandToGsp {
     /// Type generated by [`CommandToGsp::init`], to be written into the command queue buffer.
     type Command: FromBytes + AsBytes;
 
+    /// Type of the reply expected from the GSP, or [`NoReply`] for commands that don't
+    /// have a reply.
+    type Reply;
+
     /// Error type returned by [`CommandToGsp::init`].
     type InitError;
 
@@ -90,6 +113,12 @@ pub(crate) trait CommandToGsp {
     ) -> Result {
         Ok(())
     }
+
+    /// Total size of the command (including its variable-length payload) without the
+    /// [`GspMsgElement`] header.
+    fn size(&self) -> usize {
+        size_of::<Self::Command>() + self.variable_payload_len()
+    }
 }
 
 /// Trait representing messages received from the GSP.
@@ -159,12 +188,14 @@ pub(super) struct GspMem {
     /// Self-mapping page table entries.
     ptes: PteArray<{ Self::PTE_ARRAY_SIZE }>,
     /// CPU queue: the driver writes commands here, and the GSP reads them. It also contains the
-    /// write and read pointers that the CPU updates.
+    /// write and read pointers that the CPU updates. This means that the read pointer here is an
+    /// index into the GSP queue.
     ///
     /// This member is read-only for the GSP.
     pub(super) cpuq: Msgq,
     /// GSP queue: the GSP writes messages here, and the driver reads them. It also contains the
-    /// write and read pointers that the GSP updates.
+    /// write and read pointers that the GSP updates. This means that the read pointer here is an
+    /// index into the CPU queue.
     ///
     /// This member is read-only for the driver.
     pub(super) gspq: Msgq,
@@ -182,7 +213,7 @@ unsafe impl AsBytes for GspMem {}
 // that is not a problem because they are not used outside the kernel.
 unsafe impl FromBytes for GspMem {}
 
-/// Wrapper around [`GspMem`] to share it with the GPU using a [`CoherentAllocation`].
+/// Wrapper around [`GspMem`] to share it with the GPU using a [`Coherent`].
 ///
 /// This provides the low-level functionality to communicate with the GSP, including allocation of
 /// queue space to write messages to and management of read/write pointers.
@@ -193,7 +224,7 @@ unsafe impl FromBytes for GspMem {}
 ///   pointer and the GSP read pointer. This region is returned by [`Self::driver_write_area`].
 /// * The driver owns (i.e. can read from) the part of the GSP message queue between the CPU read
 ///   pointer and the GSP write pointer. This region is returned by [`Self::driver_read_area`].
-struct DmaGspMem(CoherentAllocation<GspMem>);
+struct DmaGspMem(Coherent<GspMem>);
 
 impl DmaGspMem {
     /// Allocate a new instance and map it for `dev`.
@@ -201,21 +232,20 @@ impl DmaGspMem {
         const MSGQ_SIZE: u32 = num::usize_into_u32::<{ size_of::<Msgq>() }>();
         const RX_HDR_OFF: u32 = num::usize_into_u32::<{ mem::offset_of!(Msgq, rx) }>();
 
-        let gsp_mem =
-            CoherentAllocation::<GspMem>::alloc_coherent(dev, 1, GFP_KERNEL | __GFP_ZERO)?;
+        let gsp_mem = Coherent::<GspMem>::zeroed(dev, GFP_KERNEL)?;
 
         let start = gsp_mem.dma_handle();
         // Write values one by one to avoid an on-stack instance of `PteArray`.
         for i in 0..GspMem::PTE_ARRAY_SIZE {
-            dma_write!(gsp_mem, [0]?.ptes.0[i], PteArray::<0>::entry(start, i)?);
+            dma_write!(gsp_mem, .ptes.0[i], PteArray::<0>::entry(start, i)?);
         }
 
         dma_write!(
             gsp_mem,
-            [0]?.cpuq.tx,
+            .cpuq.tx,
             MsgqTxHeader::new(MSGQ_SIZE, RX_HDR_OFF, MSGQ_NUM_PAGES)
         );
-        dma_write!(gsp_mem, [0]?.cpuq.rx, MsgqRxHeader::new());
+        dma_write!(gsp_mem, .cpuq.rx, MsgqRxHeader::new());
 
         Ok(Self(gsp_mem))
     }
@@ -226,69 +256,124 @@ impl DmaGspMem {
     /// As the message queue is a circular buffer, the region may be discontiguous in memory. In
     /// that case the second slice will have a non-zero length.
     fn driver_write_area(&mut self) -> (&mut [[u8; GSP_PAGE_SIZE]], &mut [[u8; GSP_PAGE_SIZE]]) {
-        let tx = self.cpu_write_ptr() as usize;
-        let rx = self.gsp_read_ptr() as usize;
+        let tx = self.cpu_write_ptr();
+        let rx = self.gsp_read_ptr();
+
+        // Pointer to the first entry of the CPU message queue.
+        let data = ptr::project!(mut self.0.as_mut_ptr(), .cpuq.msgq.data[0]);
+
+        let (tail_end, wrap_end) = if rx == 0 {
+            // The write area is non-wrapping, and stops at the second-to-last entry of the command
+            // queue (to leave the last one empty).
+            (MSGQ_NUM_PAGES - 1, 0)
+        } else if rx <= tx {
+            // The write area wraps and continues until `rx - 1`.
+            (MSGQ_NUM_PAGES, rx - 1)
+        } else {
+            // The write area doesn't wrap and stops at `rx - 1`.
+            (rx - 1, 0)
+        };
 
         // SAFETY:
-        // - The `CoherentAllocation` contains exactly one object.
-        // - We will only access the driver-owned part of the shared memory.
-        // - Per the safety statement of the function, no concurrent access will be performed.
-        let gsp_mem = &mut unsafe { self.0.as_slice_mut(0, 1) }.unwrap()[0];
-        // PANIC: per the invariant of `cpu_write_ptr`, `tx` is `<= MSGQ_NUM_PAGES`.
-        let (before_tx, after_tx) = gsp_mem.cpuq.msgq.data.split_at_mut(tx);
-
-        if rx <= tx {
-            // The area from `tx` up to the end of the ring, and from the beginning of the ring up
-            // to `rx`, minus one unit, belongs to the driver.
-            if rx == 0 {
-                let last = after_tx.len() - 1;
-                (&mut after_tx[..last], &mut before_tx[0..0])
-            } else {
-                (after_tx, &mut before_tx[..rx])
-            }
-        } else {
-            // The area from `tx` to `rx`, minus one unit, belongs to the driver.
-            //
-            // PANIC: per the invariants of `cpu_write_ptr` and `gsp_read_ptr`, `rx` and `tx` are
-            // `<= MSGQ_NUM_PAGES`, and the test above ensured that `rx > tx`.
-            (after_tx.split_at_mut(rx - tx).0, &mut before_tx[0..0])
+        // - `data` was created from a valid pointer, and `rx` and `tx` are in the
+        //   `0..MSGQ_NUM_PAGES` range per the invariants of `cpu_write_ptr` and `gsp_read_ptr`,
+        //   thus the created slices are valid.
+        // - The area starting at `tx` and ending at `rx - 2` modulo `MSGQ_NUM_PAGES`,
+        //   inclusive, belongs to the driver for writing and is not accessed concurrently by
+        //   the GSP.
+        // - The caller holds a reference to `self` for as long as the returned slices are live,
+        //   meaning the CPU write pointer cannot be advanced and thus that the returned area
+        //   remains exclusive to the CPU for the duration of the slices.
+        // - The created slices point to non-overlapping sub-ranges of `data` in all
+        //   branches (in the `rx <= tx` case, the second slice ends at `rx - 1` which is strictly
+        //   less than `tx` where the first slice starts; in the other cases the second slice is
+        //   empty), so creating two `&mut` references from them does not violate aliasing rules.
+        unsafe {
+            (
+                core::slice::from_raw_parts_mut(
+                    data.add(num::u32_as_usize(tx)),
+                    num::u32_as_usize(tail_end - tx),
+                ),
+                core::slice::from_raw_parts_mut(data, num::u32_as_usize(wrap_end)),
+            )
         }
     }
 
+    /// Returns the size of the region of the CPU message queue that the driver is currently allowed
+    /// to write to, in bytes.
+    fn driver_write_area_size(&self) -> usize {
+        let tx = self.cpu_write_ptr();
+        let rx = self.gsp_read_ptr();
+
+        // `rx` and `tx` are both in `0..MSGQ_NUM_PAGES` per the invariants of `gsp_read_ptr` and
+        // `cpu_write_ptr`. The minimum value case is where `rx == 0` and `tx == MSGQ_NUM_PAGES -
+        // 1`, which gives `0 + MSGQ_NUM_PAGES - (MSGQ_NUM_PAGES - 1) - 1 == 0`.
+        let slots = (rx + MSGQ_NUM_PAGES - tx - 1) % MSGQ_NUM_PAGES;
+        num::u32_as_usize(slots) * GSP_PAGE_SIZE
+    }
+
     /// Returns the region of the GSP message queue that the driver is currently allowed to read
     /// from.
     ///
     /// As the message queue is a circular buffer, the region may be discontiguous in memory. In
     /// that case the second slice will have a non-zero length.
     fn driver_read_area(&self) -> (&[[u8; GSP_PAGE_SIZE]], &[[u8; GSP_PAGE_SIZE]]) {
-        let tx = self.gsp_write_ptr() as usize;
-        let rx = self.cpu_read_ptr() as usize;
+        let tx = self.gsp_write_ptr();
+        let rx = self.cpu_read_ptr();
+
+        // Pointer to the first entry of the GSP message queue.
+        let data = ptr::project!(self.0.as_ptr(), .gspq.msgq.data[0]);
+
+        let (tail_end, wrap_end) = if rx <= tx {
+            // Read area is non-wrapping and stops right before `tx`.
+            (tx, 0)
+        } else {
+            // Read area is wrapping and stops right before `tx`.
+            (MSGQ_NUM_PAGES, tx)
+        };
 
         // SAFETY:
-        // - The `CoherentAllocation` contains exactly one object.
-        // - We will only access the driver-owned part of the shared memory.
-        // - Per the safety statement of the function, no concurrent access will be performed.
-        let gsp_mem = &unsafe { self.0.as_slice(0, 1) }.unwrap()[0];
-        // PANIC: per the invariant of `cpu_read_ptr`, `xx` is `<= MSGQ_NUM_PAGES`.
-        let (before_rx, after_rx) = gsp_mem.gspq.msgq.data.split_at(rx);
-
-        match tx.cmp(&rx) {
-            cmp::Ordering::Equal => (&after_rx[0..0], &after_rx[0..0]),
-            cmp::Ordering::Greater => (&after_rx[..tx], &before_rx[0..0]),
-            cmp::Ordering::Less => (after_rx, &before_rx[..tx]),
+        // - `data` was created from a valid pointer, and `rx` and `tx` are in the
+        //   `0..MSGQ_NUM_PAGES` range per the invariants of `gsp_write_ptr` and `cpu_read_ptr`,
+        //   thus the created slices are valid.
+        // - The area starting at `rx` and ending at `tx - 1` modulo `MSGQ_NUM_PAGES`,
+        //   inclusive, belongs to the driver for reading and is not accessed concurrently by
+        //   the GSP.
+        // - The caller holds a reference to `self` for as long as the returned slices are live,
+        //   meaning the CPU read pointer cannot be advanced and thus that the returned area
+        //   remains exclusive to the CPU for the duration of the slices.
+        unsafe {
+            (
+                core::slice::from_raw_parts(
+                    data.add(num::u32_as_usize(rx)),
+                    num::u32_as_usize(tail_end - rx),
+                ),
+                core::slice::from_raw_parts(data, num::u32_as_usize(wrap_end)),
+            )
         }
     }
 
     /// Allocates a region on the command queue that is large enough to send a command of `size`
-    /// bytes.
+    /// bytes, waiting for space to become available based on the provided timeout.
     ///
     /// This returns a [`GspCommand`] ready to be written to by the caller.
     ///
     /// # Errors
     ///
-    /// - `EAGAIN` if the driver area is too small to hold the requested command.
+    /// - `EMSGSIZE` if the command is larger than [`GSP_MSG_QUEUE_ELEMENT_SIZE_MAX`].
+    /// - `ETIMEDOUT` if space does not become available within the timeout.
     /// - `EIO` if the command header is not properly aligned.
-    fn allocate_command(&mut self, size: usize) -> Result<GspCommand<'_>> {
+    fn allocate_command(&mut self, size: usize, timeout: Delta) -> Result<GspCommand<'_>> {
+        if size_of::<GspMsgElement>() + size > GSP_MSG_QUEUE_ELEMENT_SIZE_MAX {
+            return Err(EMSGSIZE);
+        }
+        read_poll_timeout(
+            || Ok(self.driver_write_area_size()),
+            |available_bytes| *available_bytes >= size_of::<GspMsgElement>() + size,
+            Delta::from_micros(1),
+            timeout,
+        )?;
+
         // Get the current writable area as an array of bytes.
         let (slice_1, slice_2) = {
             let (slice_1, slice_2) = self.driver_write_area();
@@ -296,13 +381,6 @@ impl DmaGspMem {
             (slice_1.as_flattened_mut(), slice_2.as_flattened_mut())
         };
 
-        // If the GSP is still processing previous messages the shared region
-        // may be full in which case we will have to retry once the GSP has
-        // processed the existing commands.
-        if size_of::<GspMsgElement>() + size > slice_1.len() + slice_2.len() {
-            return Err(EAGAIN);
-        }
-
         // Extract area for the `GspMsgElement`.
         let (header, slice_1) = GspMsgElement::from_bytes_mut_prefix(slice_1).ok_or(EIO)?;
 
@@ -326,7 +404,7 @@ impl DmaGspMem {
     //
     // # Invariants
     //
-    // - The returned value is between `0` and `MSGQ_NUM_PAGES`.
+    // - The returned value is within `0..MSGQ_NUM_PAGES`.
     fn gsp_write_ptr(&self) -> u32 {
         super::fw::gsp_mem::gsp_write_ptr(&self.0)
     }
@@ -335,7 +413,7 @@ impl DmaGspMem {
     //
     // # Invariants
     //
-    // - The returned value is between `0` and `MSGQ_NUM_PAGES`.
+    // - The returned value is within `0..MSGQ_NUM_PAGES`.
     fn gsp_read_ptr(&self) -> u32 {
         super::fw::gsp_mem::gsp_read_ptr(&self.0)
     }
@@ -344,7 +422,7 @@ impl DmaGspMem {
     //
     // # Invariants
     //
-    // - The returned value is between `0` and `MSGQ_NUM_PAGES`.
+    // - The returned value is within `0..MSGQ_NUM_PAGES`.
     fn cpu_read_ptr(&self) -> u32 {
         super::fw::gsp_mem::cpu_read_ptr(&self.0)
     }
@@ -358,7 +436,7 @@ impl DmaGspMem {
     //
     // # Invariants
     //
-    // - The returned value is between `0` and `MSGQ_NUM_PAGES`.
+    // - The returned value is within `0..MSGQ_NUM_PAGES`.
     fn cpu_write_ptr(&self) -> u32 {
         super::fw::gsp_mem::cpu_write_ptr(&self.0)
     }
@@ -395,13 +473,13 @@ struct GspMessage<'a> {
 ///
 /// Provides the ability to send commands and receive messages from the GSP using a shared memory
 /// area.
+#[pin_data]
 pub(crate) struct Cmdq {
-    /// Device this command queue belongs to.
-    dev: ARef<device::Device>,
-    /// Current command sequence number.
-    seq: u32,
-    /// Memory area shared with the GSP for communicating commands and messages.
-    gsp_mem: DmaGspMem,
+    /// Inner mutex-protected state.
+    #[pin]
+    inner: Mutex<CmdqInner>,
+    /// DMA handle of the command queue's shared memory region.
+    pub(super) dma_handle: DmaAddress,
 }
 
 impl Cmdq {
@@ -421,14 +499,22 @@ impl Cmdq {
     /// Number of page table entries for the GSP shared region.
     pub(crate) const NUM_PTES: usize = size_of::<GspMem>() >> GSP_PAGE_SHIFT;
 
-    /// Creates a new command queue for `dev`.
-    pub(crate) fn new(dev: &device::Device<device::Bound>) -> Result<Cmdq> {
-        let gsp_mem = DmaGspMem::new(dev)?;
+    /// Default timeout for receiving a message from the GSP.
+    pub(super) const RECEIVE_TIMEOUT: Delta = Delta::from_secs(5);
 
-        Ok(Cmdq {
-            dev: dev.into(),
-            seq: 0,
-            gsp_mem,
+    /// Creates a new command queue for `dev`.
+    pub(crate) fn new(dev: &device::Device<device::Bound>) -> impl PinInit<Self, Error> + '_ {
+        pin_init_scope(move || {
+            let gsp_mem = DmaGspMem::new(dev)?;
+
+            Ok(try_pin_init!(Self {
+                dma_handle: gsp_mem.0.dma_handle(),
+                inner <- new_mutex!(CmdqInner {
+                    dev: dev.into(),
+                    gsp_mem,
+                    seq: 0,
+                }),
+            }))
         })
     }
 
@@ -447,34 +533,115 @@ impl Cmdq {
 
     /// Notifies the GSP that we have updated the command queue pointers.
     fn notify_gsp(bar: &Bar0) {
-        regs::NV_PGSP_QUEUE_HEAD::default()
-            .set_address(0)
-            .write(bar);
+        bar.write_reg(regs::NV_PGSP_QUEUE_HEAD::zeroed().with_address(0u32));
     }
 
-    /// Sends `command` to the GSP.
+    /// Sends `command` to the GSP and waits for the reply.
+    ///
+    /// Messages with non-matching function codes are silently consumed until the expected reply
+    /// arrives.
+    ///
+    /// The queue is locked for the entire send+receive cycle to ensure that no other command can
+    /// be interleaved.
     ///
     /// # Errors
     ///
-    /// - `EAGAIN` if there was not enough space in the command queue to send the command.
+    /// - `ETIMEDOUT` if space does not become available to send the command, or if the reply is
+    ///   not received within the timeout.
     /// - `EIO` if the variable payload requested by the command has not been entirely
     ///   written to by its [`CommandToGsp::init_variable_payload`] method.
     ///
-    /// Error codes returned by the command initializers are propagated as-is.
-    pub(crate) fn send_command<M>(&mut self, bar: &Bar0, command: M) -> Result
+    /// Error codes returned by the command and reply initializers are propagated as-is.
+    pub(crate) fn send_command<M>(&self, bar: &Bar0, command: M) -> Result<M::Reply>
     where
         M: CommandToGsp,
+        M::Reply: MessageFromGsp,
+        Error: From<M::InitError>,
+        Error: From<<M::Reply as MessageFromGsp>::InitError>,
+    {
+        let mut inner = self.inner.lock();
+        inner.send_command(bar, command)?;
+
+        loop {
+            match inner.receive_msg::<M::Reply>(Self::RECEIVE_TIMEOUT) {
+                Ok(reply) => break Ok(reply),
+                Err(ERANGE) => continue,
+                Err(e) => break Err(e),
+            }
+        }
+    }
+
+    /// Sends `command` to the GSP without waiting for a reply.
+    ///
+    /// # Errors
+    ///
+    /// - `ETIMEDOUT` if space does not become available within the timeout.
+    /// - `EIO` if the variable payload requested by the command has not been entirely
+    ///   written to by its [`CommandToGsp::init_variable_payload`] method.
+    ///
+    /// Error codes returned by the command initializers are propagated as-is.
+    pub(crate) fn send_command_no_wait<M>(&self, bar: &Bar0, command: M) -> Result
+    where
+        M: CommandToGsp<Reply = NoReply>,
+        Error: From<M::InitError>,
+    {
+        self.inner.lock().send_command(bar, command)
+    }
+
+    /// Receive a message from the GSP.
+    ///
+    /// See [`CmdqInner::receive_msg`] for details.
+    pub(crate) fn receive_msg<M: MessageFromGsp>(&self, timeout: Delta) -> Result<M>
+    where
         // This allows all error types, including `Infallible`, to be used for `M::InitError`.
         Error: From<M::InitError>,
     {
-        let command_size = size_of::<M::Command>() + command.variable_payload_len();
-        let dst = self.gsp_mem.allocate_command(command_size)?;
+        self.inner.lock().receive_msg(timeout)
+    }
+}
 
-        // Extract area for the command itself.
+/// Inner mutex protected state of [`Cmdq`].
+struct CmdqInner {
+    /// Device this command queue belongs to.
+    dev: ARef<device::Device>,
+    /// Current command sequence number.
+    seq: u32,
+    /// Memory area shared with the GSP for communicating commands and messages.
+    gsp_mem: DmaGspMem,
+}
+
+impl CmdqInner {
+    /// Timeout for waiting for space on the command queue.
+    const ALLOCATE_TIMEOUT: Delta = Delta::from_secs(1);
+
+    /// Sends `command` to the GSP, without splitting it.
+    ///
+    /// # Errors
+    ///
+    /// - `EMSGSIZE` if the command exceeds the maximum queue element size.
+    /// - `ETIMEDOUT` if space does not become available within the timeout.
+    /// - `EIO` if the variable payload requested by the command has not been entirely
+    ///   written to by its [`CommandToGsp::init_variable_payload`] method.
+    ///
+    /// Error codes returned by the command initializers are propagated as-is.
+    fn send_single_command<M>(&mut self, bar: &Bar0, command: M) -> Result
+    where
+        M: CommandToGsp,
+        // This allows all error types, including `Infallible`, to be used for `M::InitError`.
+        Error: From<M::InitError>,
+    {
+        let size_in_bytes = command.size();
+        let dst = self
+            .gsp_mem
+            .allocate_command(size_in_bytes, Self::ALLOCATE_TIMEOUT)?;
+
+        // Extract area for the command itself. The GSP message header and the command header
+        // together are guaranteed to fit entirely into a single page, so it's ok to only look
+        // at `dst.contents.0` here.
         let (cmd, payload_1) = M::Command::from_bytes_mut_prefix(dst.contents.0).ok_or(EIO)?;
 
         // Fill the header and command in-place.
-        let msg_element = GspMsgElement::init(self.seq, command_size, M::FUNCTION);
+        let msg_element = GspMsgElement::init(self.seq, size_in_bytes, M::FUNCTION);
         // SAFETY: `msg_header` and `cmd` are valid references, and not touched if the initializer
         // fails.
         unsafe {
@@ -482,16 +649,14 @@ impl Cmdq {
             command.init().__init(core::ptr::from_mut(cmd))?;
         }
 
-        // Fill the variable-length payload.
-        if command_size > size_of::<M::Command>() {
-            let mut sbuffer =
-                SBufferIter::new_writer([&mut payload_1[..], &mut dst.contents.1[..]]);
-            command.init_variable_payload(&mut sbuffer)?;
+        // Fill the variable-length payload, which may be empty.
+        let mut sbuffer = SBufferIter::new_writer([&mut payload_1[..], &mut dst.contents.1[..]]);
+        command.init_variable_payload(&mut sbuffer)?;
 
-            if !sbuffer.is_empty() {
-                return Err(EIO);
-            }
+        if !sbuffer.is_empty() {
+            return Err(EIO);
         }
+        drop(sbuffer);
 
         // Compute checksum now that the whole message is ready.
         dst.header
@@ -503,7 +668,7 @@ impl Cmdq {
 
         dev_dbg!(
             &self.dev,
-            "GSP RPC: send: seq# {}, function={}, length=0x{:x}\n",
+            "GSP RPC: send: seq# {}, function={:?}, length=0x{:x}\n",
             self.seq,
             M::FUNCTION,
             dst.header.length(),
@@ -518,6 +683,37 @@ impl Cmdq {
         Ok(())
     }
 
+    /// Sends `command` to the GSP.
+    ///
+    /// The command may be split into multiple messages if it is large.
+    ///
+    /// # Errors
+    ///
+    /// - `ETIMEDOUT` if space does not become available within the timeout.
+    /// - `EIO` if the variable payload requested by the command has not been entirely
+    ///   written to by its [`CommandToGsp::init_variable_payload`] method.
+    ///
+    /// Error codes returned by the command initializers are propagated as-is.
+    fn send_command<M>(&mut self, bar: &Bar0, command: M) -> Result
+    where
+        M: CommandToGsp,
+        Error: From<M::InitError>,
+    {
+        match SplitState::new(command)? {
+            SplitState::Single(command) => self.send_single_command(bar, command),
+            SplitState::Split(command, mut continuations) => {
+                self.send_single_command(bar, command)?;
+
+                while let Some(continuation) = continuations.next() {
+                    // Turbofish needed because the compiler cannot infer M here.
+                    self.send_single_command::<ContinuationRecord<'_>>(bar, continuation)?;
+                }
+
+                Ok(())
+            }
+        }
+    }
+
     /// Wait for a message to become available on the message queue.
     ///
     /// This works purely at the transport layer and does not interpret or validate the message
@@ -550,7 +746,7 @@ impl Cmdq {
         let (header, slice_1) = GspMsgElement::from_bytes_prefix(slice_1).ok_or(EIO)?;
 
         dev_dbg!(
-            self.dev,
+            &self.dev,
             "GSP RPC: receive: seq# {}, function={:?}, length=0x{:x}\n",
             header.sequence(),
             header.function(),
@@ -585,7 +781,7 @@ impl Cmdq {
         ])) != 0
         {
             dev_err!(
-                self.dev,
+                &self.dev,
                 "GSP RPC: receive: Call {} - bad checksum\n",
                 header.sequence()
             );
@@ -600,23 +796,21 @@ impl Cmdq {
 
     /// Receive a message from the GSP.
     ///
-    /// `init` is a closure tasked with processing the message. It receives a reference to the
-    /// message in the message queue, and a [`SBufferIter`] pointing to its variable-length
-    /// payload, if any.
-    ///
-    /// The expected message is specified using the `M` generic parameter. If the pending message
-    /// is different, `EAGAIN` is returned and the unexpected message is dropped.
+    /// The expected message type is specified using the `M` generic parameter. If the pending
+    /// message has a different function code, `ERANGE` is returned and the message is consumed.
     ///
-    /// This design is by no means final, but it is simple and will let us go through GSP
-    /// initialization.
+    /// The read pointer is always advanced past the message, regardless of whether it matched.
     ///
     /// # Errors
     ///
     /// - `ETIMEDOUT` if `timeout` has elapsed before any message becomes available.
     /// - `EIO` if there was some inconsistency (e.g. message shorter than advertised) on the
     ///   message queue.
-    /// - `EINVAL` if the function of the message was unrecognized.
-    pub(crate) fn receive_msg<M: MessageFromGsp>(&mut self, timeout: Delta) -> Result<M>
+    /// - `EINVAL` if the function code of the message was not recognized.
+    /// - `ERANGE` if the message had a recognized but non-matching function code.
+    ///
+    /// Error codes returned by [`MessageFromGsp::read`] are propagated as-is.
+    fn receive_msg<M: MessageFromGsp>(&mut self, timeout: Delta) -> Result<M>
     where
         // This allows all error types, including `Infallible`, to be used for `M::InitError`.
         Error: From<M::InitError>,
@@ -630,7 +824,17 @@ impl Cmdq {
             let (cmd, contents_1) = M::Message::from_bytes_prefix(message.contents.0).ok_or(EIO)?;
             let mut sbuffer = SBufferIter::new_reader([contents_1, message.contents.1]);
 
-            M::read(cmd, &mut sbuffer).map_err(|e| e.into())
+            M::read(cmd, &mut sbuffer)
+                .map_err(|e| e.into())
+                .inspect(|_| {
+                    if !sbuffer.is_empty() {
+                        dev_warn!(
+                            &self.dev,
+                            "GSP message {:?} has unprocessed data\n",
+                            function
+                        );
+                    }
+                })
         } else {
             Err(ERANGE)
         };
@@ -642,9 +846,4 @@ impl Cmdq {
 
         result
     }
-
-    /// Returns the DMA handle of the command queue's shared memory region.
-    pub(crate) fn dma_handle(&self) -> DmaAddress {
-        self.gsp_mem.0.dma_handle()
-    }
 }