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

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Message-ID: <64be3126-5d07-7490-28fc-20afd2635b8c@quicinc.com>
Date: Mon, 9 Dec 2024 10:59:28 +0530
From: Md Sadre Alam <quic_mdalam@...cinc.com>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>, <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 12/5/2024 5:58 PM, Bryan O'Donoghue wrote:
> 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 ... ?
Thank you for pointing that out. I'll address this in the next revision.
> 
> ---
> bod