linux-kernel - Re: [RESEND PATCH] drm/msm/a6xx: fix frequency not always being restored on GMU resume

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Message-ID: <270c4efd-8524-c389-3347-2f9c4e246b6d@codeaurora.org>
Date:   Mon, 17 Aug 2020 18:21:50 +0530
From:   Akhil P Oommen <akhilpo@...eaurora.org>
To:     Jonathan Marek <jonathan@...ek.ca>, freedreno@...ts.freedesktop.org
Cc:     David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        Sharat Masetty <smasetty@...eaurora.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <dri-devel@...ts.freedesktop.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Sean Paul <sean@...rly.run>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH] drm/msm/a6xx: fix frequency not always being
 restored on GMU resume

Why don't we move the early return in a6xx_gmu_set_freq() to 
msm_devfreq_target() instead?

-Akhil.

On 8/14/2020 12:24 AM, Jonathan Marek wrote:
> The patch reorganizing the set_freq function made it so the gmu resume
> doesn't always set the frequency, because a6xx_gmu_set_freq() exits early
> when the frequency hasn't been changed. Note this always happens when
> resuming GMU after recovering from a hang.
> 
> Use a simple workaround to prevent this from happening.
> 
> Fixes: 1f60d11423db ("drm: msm: a6xx: send opp instead of a frequency")
> 
> Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index b67b38c8fadf..bbbd00020f92 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -845,6 +845,7 @@ static void a6xx_gmu_set_initial_freq(struct msm_gpu *gpu, struct a6xx_gmu *gmu)
>   	if (IS_ERR_OR_NULL(gpu_opp))
>   		return;
>   
> +	gmu->freq = 0; /* so a6xx_gmu_set_freq() doesn't exit early */
>   	a6xx_gmu_set_freq(gpu, gpu_opp);
>   	dev_pm_opp_put(gpu_opp);
>   }
>