linux-kernel - Re: [PATCH v3 1/4] drm/msm/dpu: Move DPU encoder wide_bus

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Date:   Wed, 2 Aug 2023 21:32:51 +0200
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     Jessica Zhang <quic_jesszhan@...cinc.com>
Cc:     Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, quic_abhinavk@...cinc.com,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/4] drm/msm/dpu: Move DPU encoder wide_bus_en setting

I find this title very undescriptive, it doesn't really explain from/to
where this move is happening nor why.

On 2023-08-02 11:08:48, Jessica Zhang wrote:
> Move the setting of dpu_enc.wide_bus_en to
> dpu_encoder_virt_atomic_enable() so that it mirrors the setting of
> dpu_enc.dsc.

mirroring "the setting of dpu_enc.dsc" very much sounds like you are
mirroring _its value_, but that is not the case.  You are moving the
initialization (or just setting, because it could also be overwriting?)
to _the same place_ where .dsc is assigned.

I am pretty sure that this has a runtime impact which we discussed
before (hotplug...?) but the commit message omits that.  This is
mandatory.

- Marijn

> 
> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index d34e684a4178..3dcd37c48aac 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -1194,11 +1194,18 @@ static void dpu_encoder_virt_atomic_enable(struct drm_encoder *drm_enc,
>  	struct dpu_encoder_virt *dpu_enc = NULL;
>  	int ret = 0;
>  	struct drm_display_mode *cur_mode = NULL;
> +	struct msm_drm_private *priv = drm_enc->dev->dev_private;
> +	struct msm_display_info *disp_info;
>  
>  	dpu_enc = to_dpu_encoder_virt(drm_enc);
> +	disp_info = &dpu_enc->disp_info;
>  
>  	dpu_enc->dsc = dpu_encoder_get_dsc_config(drm_enc);
>  
> +	if (disp_info->intf_type == INTF_DP)
> +		dpu_enc->wide_bus_en = msm_dp_wide_bus_available(
> +				priv->dp[disp_info->h_tile_instance[0]]);
> +
>  	mutex_lock(&dpu_enc->enc_lock);
>  	cur_mode = &dpu_enc->base.crtc->state->adjusted_mode;
>  
> @@ -2383,10 +2390,6 @@ struct drm_encoder *dpu_encoder_init(struct drm_device *dev,
>  	timer_setup(&dpu_enc->frame_done_timer,
>  			dpu_encoder_frame_done_timeout, 0);
>  
> -	if (disp_info->intf_type == INTF_DP)
> -		dpu_enc->wide_bus_en = msm_dp_wide_bus_available(
> -				priv->dp[disp_info->h_tile_instance[0]]);
> -
>  	INIT_DELAYED_WORK(&dpu_enc->delayed_off_work,
>  			dpu_encoder_off_work);
>  	dpu_enc->idle_timeout = IDLE_TIMEOUT;
> 
> -- 
> 2.41.0
>