linux-kernel - Re: [PATCH V1] mmc: sdhci-msm: Enable MMC_CAP_AGGRESSIVE

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Message-ID: <c1ebdaf1-92bb-4f73-bca9-35246d7c10e1@oss.qualcomm.com>
Date: Wed, 21 May 2025 17:49:21 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Sarthak Garg <quic_sartgarg@...cinc.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>, linux-mmc@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_cang@...cinc.com, quic_nguyenb@...cinc.com,
        quic_rampraka@...cinc.com, quic_pragalla@...cinc.com,
        quic_sayalil@...cinc.com, quic_nitirawa@...cinc.com,
        quic_bhaskarv@...cinc.com, kernel@...cinc.com
Subject: Re: [PATCH V1] mmc: sdhci-msm: Enable MMC_CAP_AGGRESSIVE_PM for
 qualcomm controllers

On 21/05/2025 17:35, Sarthak Garg wrote:
> 
> 
> On 5/21/2025 6:25 PM, Dmitry Baryshkov wrote:
>> On Wed, May 21, 2025 at 12:46:49PM +0530, Sarthak Garg wrote:
>>>
>>>
>>> On 11/15/2024 6:53 PM, Dmitry Baryshkov wrote:
>>>> On Fri, 15 Nov 2024 at 12:23, Sarthak Garg 
>>>> <quic_sartgarg@...cinc.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 11/4/2024 4:19 PM, Dmitry Baryshkov wrote:
>>>>>> On Mon, Nov 04, 2024 at 11:37:22AM +0530, Sarthak Garg wrote:
>>>>>>> Enable MMC_CAP_AGGRESSIVE_PM for qualcomm controllers.
>>>>>>> This enables runtime PM for eMMC/SD card.
>>>>>>
>>>>>> Could you please mention, which platforms were tested with this 
>>>>>> patch?
>>>>>> Note, upstream kernel supports a lot of platforms, including 
>>>>>> MSM8974, I
>>>>>> think the oldest one, which uses SDHCI.
>>>>>>
>>>>>
>>>>> This was tested with qdu1000 platform.
>>>>
>>>> Are you sure that it won't break other platforms?
>>>>
>>>
>>> Thanks for your valuable comment.
>>> I am not sure about the older platforms so to avoid issues on older
>>> platforms we can enable this for all SDCC version 5.0 targets ?
>>
>> No, there are still a lot of platforms. Either explain why this is
>> required for all v5 platforms (and won't break those) or find some other
>> way, e.g. limit the change to QDU1000, explaining why it is _not_
>> applicable to other platforms.
>>
> 
> Thanks for your comment.

No need to.

> I agree with your concern but for me also its not possible to test on 
> all the platforms.

Sure.

> Lets say if I want to enable this caps for QDU1000 for which it has been 
> tested and on any other upcoming target after testing, then how can I 
> proceed to enable?

Let's start from the beginning: why do you want to enable it on QDU1000?

> 
> One option I had thought of was to implement this using compatible 
> string, then for all the upcoming platforms using this compatible string 
> as a fallback.
> But this doesn't look optimal to use compatible string for just one flag 
> and also this capability is not platform specific and we will be needing 
> for all the platforms. Please share your opinion on this.
> 
> Another option that I could have thought of is using device tree based 
> approach but seems that was not accepted earlier :
> https://patchwork.kernel.org/project/linux-mmc/ 
> patch/20230129023630.830764-1-chenhuiz@...s.com/
> 
> So it would be helpful if you can suggest some approach?

Worst case, just tie it to the SoC-specific compat string that is 
already a part of the bindings.


-- 
With best wishes
Dmitry