From 867621ba203027338b525af6729719c544135336 Mon Sep 17 00:00:00 2001 From: Md Sadre Alam Date: Mon, 15 Jun 2026 11:39:08 +0530 Subject: dmaengine: qcom: bam_dma: Fix command element mask field for BAM v1.6.0+ BAM version 1.6.0 and later changed the behavior of the mask field in command elements for read operations. In older BAM versions, or prior implementation assumptions, the mask field was effectively ignored for read commands. However, starting from BAM v1.6.0, the mask field for read commands is repurposed to carry the upper 4 bits of the destination address, enabling support for 36-bit addressing. For write commands, the mask field continues to function as a traditional write mask. The current driver sets mask = 0xffffffff for all command elements. While this works for write operations, it breaks read operations on BAM v1.6.0+ hardware. In such cases, the hardware interprets the upper address bits as 0xf, resulting in an invalid destination address (0xf_xxxxxxxx instead of 0x0_xxxxxxxx). This leads to failures such as NAND enumeration issues observed on platforms like IPQ5424. Fix this by assigning the mask field based on command type: - For read commands: set mask = 0 (upper address bits = 0) - For write commands: retain mask = 0xffffffff Also update the bam_cmd_element structure documentation to reflect the dual purpose of the mask field across BAM versions. This ensures correct behavior on BAM v1.6.0+ while maintaining backward compatibility with older hardware. Fixes: dfebb055f73a2 ("dmaengine: qcom: bam_dma: wrapper functions for command descriptor") Tested-by: Lakshmi Sowjanya D Signed-off-by: Md Sadre Alam Reviewed-by: Frank Li Reviewed-by: Dmitry Baryshkov Cc: stable@vger.kernel.org Signed-off-by: Varadarajan Narayanan Link: https://patch.msgid.link/20260615060908.1263171-1-varadarajan.narayanan@oss.qualcomm.com Signed-off-by: Vinod Koul --- include/linux/dma/qcom_bam_dma.h | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma/qcom_bam_dma.h b/include/linux/dma/qcom_bam_dma.h index 68fc0e643b1b..d9d07a9ab313 100644 --- a/include/linux/dma/qcom_bam_dma.h +++ b/include/linux/dma/qcom_bam_dma.h @@ -13,9 +13,12 @@ * supported by BAM DMA Engine. * * @cmd_and_addr - upper 8 bits command and lower 24 bits register address. - * @data - for write command: content to be written into peripheral register. - * for read command: dest addr to write peripheral register value. - * @mask - register mask. + * @data - For write command: content to be written into peripheral register. + * For read command: lower 32 bits of destination address. + * @mask - For write command: register write mask. + * For read command on BAM v1.6.0+: upper 4 bits of destination address. + * For read command on BAM < v1.6.0: ignored by hardware. + * Setting to 0 ensures 32-bit addressing compatibility. * @reserved - for future usage. * */ @@ -42,6 +45,10 @@ enum bam_command_type { * @addr: target address * @cmd: BAM command * @data: actual data for write and dest addr for read in le32 + * + * For BAM v1.6.0+, the mask field behavior depends on command type: + * - Write commands: mask = write mask (typically 0xffffffff) + * - Read commands: mask = upper 4 bits of destination address (0 for 32-bit) */ static inline void bam_prep_ce_le32(struct bam_cmd_element *bam_ce, u32 addr, @@ -50,7 +57,11 @@ bam_prep_ce_le32(struct bam_cmd_element *bam_ce, u32 addr, bam_ce->cmd_and_addr = cpu_to_le32((addr & 0xffffff) | ((cmd & 0xff) << 24)); bam_ce->data = data; - bam_ce->mask = cpu_to_le32(0xffffffff); + if (cmd == BAM_READ_COMMAND) + bam_ce->mask = cpu_to_le32(0x0); /* 32-bit addressing */ + else + bam_ce->mask = cpu_to_le32(0xffffffff); /* Write mask */ + bam_ce->reserved = 0; } /* @@ -60,7 +71,7 @@ bam_prep_ce_le32(struct bam_cmd_element *bam_ce, u32 addr, * @bam_ce: BAM command element * @addr: target address * @cmd: BAM command - * @data: actual data for write and dest addr for read + * @data: actual data for write and destination address for read */ static inline void bam_prep_ce(struct bam_cmd_element *bam_ce, u32 addr, -- cgit v1.2.3