linux-kernel - Re: [PATCH v3 03/38] drm/msm/dp: break up dp_display

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Message-ID: <xwvuajrm76flwhnciclz3bxzj6vmvladm4t73mr2pyrblczi6e@wbyq3x2yabrk>
Date: Mon, 25 Aug 2025 20:13:54 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Yongxing Mou <yongxing.mou@....qualcomm.com>
Cc: Rob Clark <robin.clark@....qualcomm.com>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Sean Paul <sean@...rly.run>,
        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,
        Abhinav Kumar <quic_abhinavk@...cinc.com>
Subject: Re: [PATCH v3 03/38] drm/msm/dp: break up dp_display_enable into two
 parts

On Mon, Aug 25, 2025 at 10:15:49PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhinavk@...cinc.com>
> 
> dp_display_enable() currently re-trains the link if needed and then
> enables the pixel clock, programs the controller to start sending the
> pixel stream. Split these two parts into prepare/enable APIs, to support
> MST bridges_enable insert the MST payloads funcs between enable
> stream_clks and program register.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> Signed-off-by: Yongxing Mou <yongxing.mou@....qualcomm.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_ctrl.c    |  51 ++++++++++------
>  drivers/gpu/drm/msm/dp/dp_ctrl.h    |   3 +-
>  drivers/gpu/drm/msm/dp/dp_display.c | 113 ++++++++++++++++++++++++------------
>  drivers/gpu/drm/msm/dp/dp_display.h |   1 +
>  4 files changed, 113 insertions(+), 55 deletions(-)
> 
>  void msm_dp_bridge_mode_set(struct drm_bridge *drm_bridge,
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 60094061c1029bc7a06ffaa80d9403b40aa07eb1..2fbf16f27842bb7639efaa2baecac7bdf8908432 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -20,6 +20,7 @@ struct msm_dp {
>  	bool link_ready;
>  	bool audio_enabled;
>  	bool power_on;
> +	bool prepared;

Why do you need this? The msm_dp_display_prepare() function can only be
called from within the atomic_enable() callback, which is not supposed
to fail and which is always called in pairs with the atomic_disable()
callback.

>  	unsigned int connector_type;
>  	bool is_edp;
>  	bool internal_hpd;
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry