linux-kernel - Re: [Freedreno] [PATCH v1 1/5] drm/msm/dp: remove pm_runtime_xxx() from dp

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Message-ID: <ebafc2ec-947f-0c9f-4ac3-14f66468b63c@linaro.org>
Date:   Mon, 10 Jul 2023 21:00:50 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc:     dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, swboyd@...omium.org, dianders@...omium.org,
        vkoul@...nel.org, daniel@...ll.ch, airlied@...il.com,
        agross@...nel.org, andersson@...nel.org, quic_sbillaka@...cinc.com,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        marijn.suijten@...ainline.org, quic_jesszhan@...cinc.com,
        freedreno@...ts.freedesktop.org
Subject: Re: [Freedreno] [PATCH v1 1/5] drm/msm/dp: remove pm_runtime_xxx()
 from dp_power.c

On 10/07/2023 20:25, Kuogee Hsieh wrote:
> 
> On 7/9/2023 1:32 PM, Abhinav Kumar wrote:
>>
>>
>> On 7/9/2023 11:00 AM, Dmitry Baryshkov wrote:
>>> On Sun, 9 Jul 2023 at 20:22, Abhinav Kumar 
>>> <quic_abhinavk@...cinc.com> wrote:
>>>>
>>>>
>>>>
>>>> On 7/7/2023 5:06 PM, Dmitry Baryshkov wrote:
>>>>> On 08/07/2023 02:52, Kuogee Hsieh wrote:
>>>>>> Since both pm_runtime_resume() and pm_runtime_suspend() are not
>>>>>> populated at dp_pm_ops. Those pm_runtime_get/put() functions within
>>>>>> dp_power.c will not have any effects in addition to increase/decrease
>>>>>> power counter.
>>>>>
>>>>> Lie.
>>>>>
>>>>
>>>> Even if the commit text is incorrect, review comments like this are not
>>>> helping the patch nor the author and will just get ignored anyway.
>>>
>>> The review comment might be overreacting, excuse me. I was really
>>> impressed by the commit message, which contradicts the basic source
>>> code. pm_runtime_get() does a lot more than just increasing the power
>>> counter.
>>>
>>
>> It says within dp_power.c. Nonetheless, please let us know what is 
>> missing in the context of this patch like Bjorn did to make it an 
>> effective review and we can correct it. In its current form, the 
>> review comment is adding no value.
>>
> I am new in pm.
> 
> Any recommendation to revise this commit test?

I'd say, squash patches 1 and 2 and then state in the commit message 
that you are changing pm_runtime code paths because you want to power up 
the device from the runtime callbacks rather than just waking up the 
device in the power up path.

Generally it is much easier to justify changing from A to B rather than 
just dropping A and then adding B.

> 
>>>>>> Also pm_runtime_xxx() should be executed at top
>>>>>> layer.
>>>>>
>>>>> Why?
>>>>>
>>>>
>>>> I guess he meant to centralize this around dp_display.c. Will elaborate
>>>> while posting the next rev.
>>>>
>>>>>>
>>>>>> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
>>>>>> ---
>>>>>>    drivers/gpu/drm/msm/dp/dp_power.c | 9 ---------
>>>>>>    1 file changed, 9 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_power.c
>>>>>> b/drivers/gpu/drm/msm/dp/dp_power.c
>>>>>> index 5cb84ca..ed2f62a 100644
>>>>>> --- a/drivers/gpu/drm/msm/dp/dp_power.c
>>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_power.c
>>>>>> @@ -152,8 +152,6 @@ int dp_power_client_init(struct dp_power 
>>>>>> *dp_power)
>>>>>>        power = container_of(dp_power, struct dp_power_private, 
>>>>>> dp_power);
>>>>>> -    pm_runtime_enable(power->dev);
>>>>>> -
>>>>>>        return dp_power_clk_init(power);
>>>>>>    }
>>>>>> @@ -162,8 +160,6 @@ void dp_power_client_deinit(struct dp_power
>>>>>> *dp_power)
>>>>>>        struct dp_power_private *power;
>>>>>>        power = container_of(dp_power, struct dp_power_private, 
>>>>>> dp_power);
>>>>>> -
>>>>>> -    pm_runtime_disable(power->dev);
>>>>>>    }
>>>>>>    int dp_power_init(struct dp_power *dp_power)
>>>>>> @@ -173,11 +169,7 @@ int dp_power_init(struct dp_power *dp_power)
>>>>>>        power = container_of(dp_power, struct dp_power_private, 
>>>>>> dp_power);
>>>>>> -    pm_runtime_get_sync(power->dev);
>>>>>> -
>>>>>>        rc = dp_power_clk_enable(dp_power, DP_CORE_PM, true);
>>>>>> -    if (rc)
>>>>>> -        pm_runtime_put_sync(power->dev);
>>>>>>        return rc;
>>>>>>    }
>>>>>> @@ -189,7 +181,6 @@ int dp_power_deinit(struct dp_power *dp_power)
>>>>>>        power = container_of(dp_power, struct dp_power_private, 
>>>>>> dp_power);
>>>>>>        dp_power_clk_enable(dp_power, DP_CORE_PM, false);
>>>>>> -    pm_runtime_put_sync(power->dev);
>>>>>>        return 0;
>>>>>>    }
>>>>>
>>>
>>>
>>>

-- 
With best wishes
Dmitry