Re: [PATCH v4 1/7] dma: qcom: bam_dma: Fix command element mask field for BAM v1.6.0+

[Md Sadre Alam]

Hi,

On 2/6/2026 10:42 PM, Krzysztof Kozlowski wrote:
> On 06/02/2026 11:01, Md Sadre Alam wrote:
> > BAM version 1.6.0 and later changed the behavior of the mask field in
> > command elements for read operations. In newer BAM versions, the mask
> > field for read commands contains the upper 4 bits of the destination
> > address to support 36-bit addressing, while for write commands it
> > continues to function as a traditional write mask.
> >
> > This change causes NAND enumeration failures on platforms like IPQ5424
>
> Please do not use "This commit/patch/change", but imperative mood. See
> longer explanation here:
> https://elixir.bootlin.com/linux/v6.16/source/Documentation/process/submitting-patches.rst#L94
Ok
> > that use BAM v1.6.0+, because the current code sets mask=0xffffffff
> > for all commands. For read commands on newer BAM versions, this results
> > in the hardware interpreting the destination address as 0xf_xxxxxxxx
> > (invalid high memory) instead of the intended 0x0_xxxxxxxx address.
> >
> > Fixed this issue by:
> > 1. Updating the bam_cmd_element structure documentation to reflect the
> >     dual purpose of the mask field
> > 2. Modifying bam_prep_ce_le32() to set appropriate mask values based on
> >     command type:
> >     - For read commands: mask = 0 (32-bit addressing, upper bits = 0)
> >     - For write commands: mask = 0xffffffff (traditional write mask)
> > 3. Maintaining backward compatibility with older BAM versions
> >
> > This fix enables proper NAND functionality on IPQ5424 and other platforms
> > using BAM v1.6.0+ while preserving compatibility with existing systems.
>
> Fixes tag? CC-stable?

This patch is not fixing an existing commit. This is to address the 
update in the newer version of the hardware.

> Why is this part of DTS patchset? Do not combine independent work, you
> only make it difficult for maintainers to handle your work.

Will post a new version with the driver change as a separate patch.

Thanks
Alam