linux-kernel - Re: [PATCH RFC RFT] drm/msm: adreno: attach the GMU device to a driver

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Message-ID: <f5041496-ee83-479a-995f-79b6952bcafe@linaro.org>
Date: Fri, 31 Oct 2025 09:38:15 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Akhil P Oommen <akhilpo@....qualcomm.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 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>
Subject: Re: [PATCH RFC RFT] drm/msm: adreno: attach the GMU device to a
 driver

Hi,

On 10/30/25 22:29, Akhil P Oommen wrote:
> On 10/22/2025 6:14 PM, Neil Armstrong wrote:
>> Due to the sync_state is enabled by default in pmdomain & CCF since v6.17,
>> the GCC and GPUCC sync_state would stay pending, leaving the resources in
>> full performance:
>> gcc-x1e80100 100000.clock-controller: sync_state() pending due to 3d6a000.gmu
>> gpucc-x1e80100 3d90000.clock-controller: sync_state() pending due to 3d6a000.gmu
>>
>> In order to fix this state and allow the GMU to be properly
>> probed, let's add a proper driver for the GMU and add it to
>> the MSM driver components.
>>
>> Only the proper GMU has been tested since I don't have
>> access to hardware with a GMU wrapper.
>>
>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>> ---
>>   drivers/gpu/drm/msm/adreno/a6xx_gmu.c      | 354 ++++++++++++++---------------
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c      |   6 -
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.h      |   3 -
>>   drivers/gpu/drm/msm/adreno/adreno_device.c |   4 +
>>   drivers/gpu/drm/msm/adreno/adreno_gpu.h    |   4 +
>>   drivers/gpu/drm/msm/msm_drv.c              |  16 +-
>>   6 files changed, 192 insertions(+), 195 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>> index fc62fef2fed8..6e7c3e627509 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>> @@ -1859,11 +1859,14 @@ void a6xx_gmu_sysprof_setup(struct msm_gpu *gpu)
>>   	pm_runtime_put(&gpu->pdev->dev);
>>   }
>>   
>> -void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu)
>> +static void a6xx_gmu_unbind(struct device *dev, struct device *master, void *data)
>>   {
> 
> I feel we should keep gmu and gmu_wrapper implementations separate. It
> is already overloaded. How about adding a separate gmu_wrapper_bind_ops
> and keep it in the match data?

Good idea, will try something like that.

> 
>> -	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct msm_drm_private *priv = dev_get_drvdata(master);
>> +	struct msm_gpu *gpu = priv->gpu;
> 
> << snip >>
> 
>>   static inline uint32_t get_wptr(struct msm_ringbuffer *ring)
>>   {
>> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
>> index 7e977fec4100..0618da7e8b40 100644
>> --- a/drivers/gpu/drm/msm/msm_drv.c
>> +++ b/drivers/gpu/drm/msm/msm_drv.c
>> @@ -998,18 +998,30 @@ static const struct of_device_id msm_gpu_match[] = {
>>   	{ },
>>   };
>>   
>> +static const struct of_device_id msm_gmu_match[] = {
>> +	{ .compatible = "qcom,adreno-gmu" },
>> +	{ .compatible = "qcom,adreno-gmu-wrapper" },
>> +	{ },
>> +};
>> +
>>   static int add_gpu_components(struct device *dev,
>>   			      struct component_match **matchptr)
>>   {
>> -	struct device_node *np;
>> +	struct device_node *np, *gmu;
>>   
>>   	np = of_find_matching_node(NULL, msm_gpu_match);
>>   	if (!np)
>>   		return 0;
>>   
>> -	if (of_device_is_available(np) && adreno_has_gpu(np))
>> +	if (of_device_is_available(np) && adreno_has_gpu(np)) {
>>   		drm_of_component_match_add(dev, matchptr, component_compare_of, np);
>>   
>> +		gmu = of_find_matching_node(NULL, msm_gmu_match);
> 
> Instead of this, we can probably use the gmu phandle from "qcom,gmu"
> property? That is quicker and also doesn't assume that there is only a
> single GPU.

Ack you're right, let's do this since we have the GPU node already.

> 
>> +		if (of_device_is_available(gmu))
>> +			drm_of_component_match_add(dev, matchptr, component_compare_of, gmu);
>> +		of_node_put(gmu);
> I think you missed the recently added headless support. Please check
> separate_gpu_kms modparam and msm_gpu_probe().

I saw it but seems I probably forgot the check if it's still functional,
will double check.

Thanks,
Neil

> 
> -Akhil
> 
>> +	}
>> +
>>   	of_node_put(np);
>>   
>>   	return 0;
>>
>> ---
>> base-commit: 211ddde0823f1442e4ad052a2f30f050145ccada
>> change-id: 20251022-topic-adreno-attach-gmu-to-driver-e47025fd7ebb
>>
>> Best regards,