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

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Message-ID: <3d3a3b14-e305-439a-b6bd-2339202ad66d@kernel.org>
Date: Mon, 9 Feb 2026 13:06:45 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Md Sadre Alam <quic_mdalam@...cinc.com>, andersson@...nel.org,
 konradybcio@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, vkoul@...nel.org, Frank.Li@...nel.org,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org
Cc: quic_varada@...cinc.com
Subject: Re: [PATCH v4 1/7] dma: qcom: bam_dma: Fix command element mask field
 for BAM v1.6.0+

On 09/02/2026 12:43, Md Sadre Alam wrote:
>>> 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.

Then "this fix" is misleading. Either you fix or not fix.


Best regards,
Krzysztof