linux-kernel - Re: drm/msm/dpu: Correct dpu encoder spinlock initialization

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Date:   Mon, 24 Jun 2019 15:26:07 -0700
From:   Jeykumar Sankaran <jsanka@...eaurora.org>
To:     Shubhashree Dhar <dhar@...eaurora.org>
Cc:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, robdclark@...il.com,
        seanpaul@...omium.org, hoegsberg@...omium.org,
        abhinavk@...eaurora.org, chandanu@...eaurora.org,
        nganji@...eaurora.org, jshekhar@...eaurora.org
Subject: Re: drm/msm/dpu: Correct dpu encoder spinlock initialization

On 2019-06-23 23:27, Shubhashree Dhar wrote:
> dpu encoder spinlock should be initialized during dpu encoder
> init instead of dpu encoder setup which is part of commit.
> There are chances that vblank control uses the uninitialized
> spinlock if not initialized during encoder init.
Not much can be done if someone is performing a vblank operation
before encoder_setup is done.
Can you point to the path where this lock is acquired before
the encoder_setup?

Thanks
Jeykumar S.
> 
> Change-Id: I5a18b95fa47397c834a266b22abf33a517b03a4e
> Signed-off-by: Shubhashree Dhar <dhar@...eaurora.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 5f085b5..22938c7 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -2195,8 +2195,6 @@ int dpu_encoder_setup(struct drm_device *dev, 
> struct
> drm_encoder *enc,
>  	if (ret)
>  		goto fail;
> 
> -	spin_lock_init(&dpu_enc->enc_spinlock);
> -
>  	atomic_set(&dpu_enc->frame_done_timeout, 0);
>  	timer_setup(&dpu_enc->frame_done_timer,
>  			dpu_encoder_frame_done_timeout, 0);
> @@ -2250,6 +2248,7 @@ struct drm_encoder *dpu_encoder_init(struct
> drm_device *dev,
> 
>  	drm_encoder_helper_add(&dpu_enc->base, &dpu_encoder_helper_funcs);
> 
> +	spin_lock_init(&dpu_enc->enc_spinlock);
>  	dpu_enc->enabled = false;
> 
>  	return &dpu_enc->base;

-- 
Jeykumar S