linux-kernel - Re: [PATCH v3] i2c: i2c-qcom-geni: Parse Error correctly in i2c GSI mode

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Message-ID: <6bacd2be-14d4-49cc-9c98-7010a5f9f9bc@quicinc.com>
Date: Fri, 8 Mar 2024 14:01:07 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Andi Shyti <andi.shyti@...nel.org>
CC: <konrad.dybcio@...aro.org>, <andersson@...nel.org>, <vkoul@...nel.org>,
        <wsa@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-i2c@...r.kernel.org>, <quic_vdadhani@...cinc.com>
Subject: Re: [PATCH v3] i2c: i2c-qcom-geni: Parse Error correctly in i2c GSI
 mode



On 3/8/2024 12:32 PM, Andi Shyti wrote:
> Hi Mukesh,
> 
> ...
> 
>>>> Fixes: d8703554f4de ("i2c: qcom-geni: Add support for GPI DMA")
>>>
>>> I still don't understand what's the fix here. You are making a
>>> generic DMA error to be more specific... where is the bug? What
>>> exactly is broken now?
>>>
>> This is about being particular while reporting specific error.
>> Like i mentioned, instead of generic DMA transfer error, it should be
>> particular error 1) NACK 2) BUT_PROTO 3)ARB_LOST.
>> Ofcourse when data transfer via DMA fails, it can be considered as
>> DMA Txfer fail.
>> In summary so far driver was considering all failure as txfer failure,
>> but i2c has errors which are kind of response/condition on the bus.
> 
> I understand that, but what I need to know is: does the system
> crash? does the system act in unexpected way?
> 
> Moving from "you received an error" to "you received a nack" is
> not a fix, it's an improvement and it should not have the Fixes
> tag.
> 
> Having the Fixes tag decides which path this patch will take to
> to reach upstream. It's important because after it gets to
> upstream other people will take your patch and backport it older
> kernels.
> 
> I want to avoid this extra work when not necessary.
> 

Sure, then i think i should be removing fixes tag. It's not a crash but
it's an improvement. That being said, i think don't need to CC stable 
kernel list and i should remove fixes tag ?

>> Sorry if it confusing still, but please let me know if anything required to
>> be updated in  commit log which can bring clarity.
>>
>>> Besides, keep in mind, that commits with fixes tags get
>>> backported to older kernels (this one dates back to 5.18) and you
>>> should also Cc the stable mailing list:
>>>
>>> Cc: <stable@...r.kernel.org> # v5.18+
>>
>> Sure, will add into CC. was waiting for reviewed-by tag.
> 
> No need to resend.

ok, sure.

> 
> Thanks,
> Andi