linux-kernel - Re: [PATCH 12/17] drm/msm: Skip devfreq IDLE when possible

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Message-ID: <vng6tut4sv3zfbwogsb74omqsbqutpeskqdnezbs4ftsanqyb4@nv35r7mqmcva>
Date: Tue, 22 Jul 2025 16:50:26 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Akhil P Oommen <akhilpo@....qualcomm.com>
Cc: 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>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/17] drm/msm: Skip devfreq IDLE when possible

On Sun, Jul 20, 2025 at 05:46:13PM +0530, Akhil P Oommen wrote:
> When IFPC is supported, devfreq idling is redundant and adds
> unnecessary pm suspend/wake latency. So skip it when IFPC is
> supported.

With this in place we have a dummy devfreq instance which does nothing.
Wouldn't it be better to skip registering devfreq if IFPC is supported
on the platform?

> 
> Signed-off-by: Akhil P Oommen <akhilpo@....qualcomm.com>
> ---
>  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> index 2e1d5c3432728cde15d91f69da22bb915588fe86..53ef2add5047e7d6b6371af949cab36ce8409372 100644
> --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> @@ -4,6 +4,7 @@
>   * Author: Rob Clark <robdclark@...il.com>
>   */
>  
> +#include "adreno/adreno_gpu.h"
>  #include "msm_gpu.h"
>  #include "msm_gpu_trace.h"
>  
> @@ -300,6 +301,8 @@ void msm_devfreq_active(struct msm_gpu *gpu)
>  	if (!has_devfreq(gpu))
>  		return;
>  
> +	if (to_adreno_gpu(gpu)->info->quirks & ADRENO_QUIRK_IFPC)
> +		return;
>  	/*
>  	 * Cancel any pending transition to idle frequency:
>  	 */
> @@ -370,6 +373,9 @@ void msm_devfreq_idle(struct msm_gpu *gpu)
>  	if (!has_devfreq(gpu))
>  		return;
>  
> +	if (to_adreno_gpu(gpu)->info->quirks & ADRENO_QUIRK_IFPC)
> +		return;
> +
>  	msm_hrtimer_queue_work(&df->idle_work, ms_to_ktime(1),
>  			       HRTIMER_MODE_REL);
>  }
> 
> -- 
> 2.50.1
> 

-- 
With best wishes
Dmitry