linux-kernel - Re: [PATCH v2] dmaengine: qcom: bam_dma: Avoid writing unavailable register

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Message-ID: <2afca6ca-10eb-43b3-8730-386d6ca84b60@linaro.org>
Date: Thu, 5 Dec 2024 12:28:26 +0000
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Md Sadre Alam <quic_mdalam@...cinc.com>, vkoul@...nel.org,
 martin.petersen@...cle.com, kees@...nel.org, av2082000@...il.com,
 fenghua.yu@...el.com, linux-arm-msm@...r.kernel.org,
 dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: quic_varada@...cinc.com, quic_srichara@...cinc.com
Subject: Re: [PATCH v2] dmaengine: qcom: bam_dma: Avoid writing unavailable
 register

On 05/12/2024 12:00, Md Sadre Alam wrote:

The commit log:

> Avoid writing unavailable register in BAM-Lite mode.
> BAM_DESC_CNT_TRSHLD register is unavailable in BAM-Lite
> mode. Its only available in BAM-NDP mode. So avoid writing

and the action taken in the code:

> +	if (bdev->bam_revision >= BAM_LITE && bdev->bam_revision < BAM_NDP)
> +		writel_relaxed(DEFAULT_CNT_THRSHLD,

Really don't match up. You've said in your commit log 
BAM_DESC_CNT_TRSHLD is unavailable to the LITE module but, then you say 
if (bam_revision >= BAM_LITE...)

How can checking if the revision == BAM_LITE match up with the stated 
objective in your commit log => _not_ writing to DEFAULT_CNT_THRSHLD in 
lite mode ... ?

---
bod