linux-kernel - Re: [PATCH 04/17] drm/msm/a6xx: Poll additional DRV status

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Message-ID: <ae143353-b979-452a-be29-0c64fd90dfd0@oss.qualcomm.com>
Date: Thu, 24 Jul 2025 13:39:25 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Akhil P Oommen <akhilpo@....qualcomm.com>,
        Rob Clark <robin.clark@....qualcomm.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/17] drm/msm/a6xx: Poll additional DRV status

On 7/23/25 9:28 PM, Akhil P Oommen wrote:
> On 7/23/2025 3:31 PM, Konrad Dybcio wrote:
>> On 7/20/25 2:16 PM, Akhil P Oommen wrote:
>>> A7XX_GEN2 generation has additional TCS slots. Poll the respective
>>> DRV status registers before pm suspend.
>>>
>>> Signed-off-by: Akhil P Oommen <akhilpo@....qualcomm.com>
>>> ---
>>>  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 16 ++++++++++++++++
>>>  1 file changed, 16 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>> index 790ef2f94a0b0cd40433d7edb6a89e4f04408bf5..3bebb6dd7059782ceca29f2efd2acee24d3fc930 100644
>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>> @@ -987,6 +987,22 @@ static void a6xx_gmu_rpmh_off(struct a6xx_gmu *gmu)
>>>  		val, (val & 1), 100, 10000);
>>>  	gmu_poll_timeout_rscc(gmu, REG_A6XX_RSCC_TCS3_DRV0_STATUS + seqmem_off,
>>>  		val, (val & 1), 100, 1000);
> 
> 1000us here is a typo and I copied the same mistake below. I will update
> all of these timeout values to a common 10000us in the next revision.
> 
>>> +
>>> +	if (!adreno_is_a740_family(adreno_gpu))
>>> +		return;
>>> +
>>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS4_DRV0_STATUS + seqmem_off,
>>> +		val, (val & 1), 100, 10000);
>>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS5_DRV0_STATUS + seqmem_off,
>>> +		val, (val & 1), 100, 10000);
>>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS6_DRV0_STATUS + seqmem_off,
>>> +		val, (val & 1), 100, 10000);
>>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS7_DRV0_STATUS + seqmem_off,
>>> +		val, (val & 1), 100, 1000);
>>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS8_DRV0_STATUS + seqmem_off,
>>> +		val, (val & 1), 100, 10000);
>>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS9_DRV0_STATUS + seqmem_off,
>>> +		val, (val & 1), 100, 1000);
>>
>> FWIW there are places downstream where it polls for 1 ms
>> (gen7_gmu_pwrctrl_suspend) / 2 ms (gen7_gmu_power_off) ms (as opposed
>> to 1 or 10 ms here), but the timeouts are all the same across registers
>> (unlike TCS3 and TCS9 above)
>>
>> Ultimately it's a timeout, so a value too big shouldn't matter, but
>> let's make sure the other threshold is ok
> 
> They are fine. We can try to reduce the timeout 2ms in a separate patch
> outside of this series.

Great, thanks for confirming!

Konrad