linux-kernel - Re: [PATCH v2 04/12] drm/msm/dp: Move link training to atomic

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Message-ID: <e217fb72-36e4-4222-b5da-9608af57c665@oss.qualcomm.com>
Date: Sat, 9 Aug 2025 03:45:22 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Rob Clark <robin.clark@....qualcomm.com>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Dmitry Baryshkov
 <lumag@...nel.org>, Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yongxing Mou <quic_yongmou@...cinc.com>
Subject: Re: [PATCH v2 04/12] drm/msm/dp: Move link training to
 atomic_enable()

On 09/08/2025 03:35, Jessica Zhang wrote:
> Currently, the DP link training is being done during HPD. Move
> link training to atomic_enable() in accordance with the atomic_enable()
> documentation.
> 
> Link disabling is already done in atomic_post_disable() (as part of the
> dp_ctrl_off_link_stream() helper).
> 
> Finally, call the plug/unplug handlers directly in hpd_notify() instead
> of queueing them in the event thread so that they aren't preempted by
> other events.

This feels like two unrelated changes.

> 
> Signed-off-by: Jessica Zhang <jessica.zhang@....qualcomm.com>
> ---
>   drivers/gpu/drm/msm/dp/dp_display.c | 15 ++++++++-------
>   1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index e2556de99894..c849befe58f0 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -427,11 +427,6 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
>   	msm_dp_link_psm_config(dp->link, &dp->panel->link_info, false);
>   
>   	msm_dp_link_reset_phy_params_vx_px(dp->link);
> -	rc = msm_dp_ctrl_on_link(dp->ctrl);
> -	if (rc) {
> -		DRM_ERROR("failed to complete DP link training\n");
> -		goto end;
> -	}
>   
>   	msm_dp_add_event(dp, EV_USER_NOTIFICATION, true, 0);
>   
> @@ -1680,6 +1675,12 @@ void msm_dp_bridge_atomic_enable(struct drm_bridge *drm_bridge,
>   		force_link_train = true;
>   	}
>   
> +	rc = msm_dp_ctrl_on_link(msm_dp_display->ctrl);
> +	if (rc) {
> +		DRM_ERROR("Failed link training (rc=%d)\n", rc);
> +		dp->connector->state->link_status = DRM_LINK_STATUS_BAD;
> +	}
> +
>   	msm_dp_display_enable(msm_dp_display, force_link_train);
>   
>   	rc = msm_dp_display_post_enable(dp);
> @@ -1839,7 +1840,7 @@ void msm_dp_bridge_hpd_notify(struct drm_bridge *bridge,
>   		return;
>   
>   	if (!msm_dp_display->link_ready && status == connector_status_connected)
> -		msm_dp_add_event(dp, EV_HPD_PLUG_INT, 0, 0);
> +		msm_dp_hpd_plug_handle(dp, 0);
>   	else if (msm_dp_display->link_ready && status == connector_status_disconnected)
> -		msm_dp_add_event(dp, EV_HPD_UNPLUG_INT, 0, 0);
> +		msm_dp_hpd_unplug_handle(dp, 0);
>   }
> 


-- 
With best wishes
Dmitry