linux-kernel - Re: [PATCH v4 4/7] drm/msm/adreno: Add module param to disable ACD

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Message-ID: <e934d116-f8ab-4efd-947c-e5c34b102409@oss.qualcomm.com>
Date: Thu, 9 Jan 2025 14:18:31 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Rob Clark
 <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Maya Matuszczyk <maccraft123mc@...il.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 4/7] drm/msm/adreno: Add module param to disable ACD

On 8.01.2025 9:40 PM, Akhil P Oommen wrote:
> Add a module param to disable ACD which will help to quickly rule it
> out for any GPU issues.
> 
> Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gmu.c      | 7 +++++++
>  drivers/gpu/drm/msm/adreno/adreno_device.c | 4 ++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index 1f213a0fc61b..ce08eed572c8 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -1475,6 +1475,13 @@ static int a6xx_gmu_acd_probe(struct a6xx_gmu *gmu)
>  	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
>  	struct msm_gpu *gpu = &adreno_gpu->base;
>  	int ret, i, cmd_idx = 0;
> +	extern bool disable_acd;
> +
> +	/* Skip ACD probe if requested via module param */
> +	if (disable_acd) {
> +		DRM_DEV_ERROR(gmu->dev, "Skipping GPU ACD probe\n");
> +		return 0;
> +	}
>  
>  	cmd->version = 1;
>  	cmd->stride = 1;
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
> index 236b25c094cd..f4552b8c6767 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_device.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
> @@ -24,6 +24,10 @@ int enable_preemption = -1;
>  MODULE_PARM_DESC(enable_preemption, "Enable preemption (A7xx only) (1=on , 0=disable, -1=auto (default))");
>  module_param(enable_preemption, int, 0600);
>  
> +bool disable_acd;
> +MODULE_PARM_DESC(disable_acd, "Forcefully disable GPU ACD");
> +module_param_unsafe(disable_acd, bool, 0600);

IIUC 0600 makes it sysfs-writeable, which we don't want, as it takes
effect during probe (meaning booting with =0 and writing 1 later on
has no effect)

Konrad