diff options
| author | Akhil P Oommen <akhilpo@oss.qualcomm.com> | 2026-03-27 05:43:50 +0530 |
|---|---|---|
| committer | Rob Clark <robin.clark@oss.qualcomm.com> | 2026-03-31 13:47:28 -0700 |
| commit | dc78b35d5ec09d1b0b8a937e6e640d2c5a030915 (patch) | |
| tree | 85df23255848524e2c9bfe1ce153298a06b10d9a /drivers/gpu/drm/msm | |
| parent | 47cbfe2608314b833ad61a65827d8fb363bc2d2d (diff) | |
| download | lwn-dc78b35d5ec09d1b0b8a937e6e640d2c5a030915.tar.gz lwn-dc78b35d5ec09d1b0b8a937e6e640d2c5a030915.zip | |
drm/msm/a6xx: Use barriers while updating HFI Q headers
To avoid harmful compiler optimizations and IO reordering in the HW, use
barriers and READ/WRITE_ONCE helpers as necessary while accessing the HFI
queue index variables.
Fixes: 4b565ca5a2cb ("drm/msm: Add A6XX device support")
Signed-off-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/714653/
Message-ID: <20260327-a8xx-gpu-batch2-v2-1-2b53c38d2101@oss.qualcomm.com>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Diffstat (limited to 'drivers/gpu/drm/msm')
| -rw-r--r-- | drivers/gpu/drm/msm/adreno/a6xx_hfi.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c index 53cfdf4e6c34..4f5dbf46132b 100644 --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c @@ -34,7 +34,7 @@ static int a6xx_hfi_queue_read(struct a6xx_gmu *gmu, struct a6xx_hfi_queue_header *header = queue->header; u32 i, hdr, index = header->read_index; - if (header->read_index == header->write_index) { + if (header->read_index == READ_ONCE(header->write_index)) { header->rx_request = 1; return 0; } @@ -62,7 +62,10 @@ static int a6xx_hfi_queue_read(struct a6xx_gmu *gmu, if (!gmu->legacy) index = ALIGN(index, 4) % header->size; - header->read_index = index; + /* Ensure all memory operations are complete before updating the read index */ + dma_mb(); + + WRITE_ONCE(header->read_index, index); return HFI_HEADER_SIZE(hdr); } @@ -74,7 +77,7 @@ static int a6xx_hfi_queue_write(struct a6xx_gmu *gmu, spin_lock(&queue->lock); - space = CIRC_SPACE(header->write_index, header->read_index, + space = CIRC_SPACE(header->write_index, READ_ONCE(header->read_index), header->size); if (space < dwords) { header->dropped++; @@ -95,7 +98,10 @@ static int a6xx_hfi_queue_write(struct a6xx_gmu *gmu, queue->data[index] = 0xfafafafa; } - header->write_index = index; + /* Ensure all memory operations are complete before updating the write index */ + dma_mb(); + + WRITE_ONCE(header->write_index, index); spin_unlock(&queue->lock); gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET, 0x01); |