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Message-ID: <6bfc8bf9-c9ce-e58a-d081-bf84e332963f@quicinc.com>
Date:   Wed, 10 Aug 2022 11:06:32 -0700
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Subject: Re: [PATCH v2] drm/msm/dp: check hpd_state before push idle pattern
 at dp_bridge_disable()
Content-Language: en-US
To:     Kuogee Hsieh <quic_khsieh@quicinc.com>, <robdclark@gmail.com>,
        <sean@poorly.run>, <swboyd@chromium.org>, <dianders@chromium.org>,
        <vkoul@kernel.org>, <daniel@ffwll.ch>, <airlied@linux.ie>,
        <agross@kernel.org>, <dmitry.baryshkov@linaro.org>,
        <bjorn.andersson@linaro.org>
CC:     <quic_aravindh@quicinc.com>, <quic_sbillaka@quicinc.com>,
        <freedreno@lists.freedesktop.org>,
        <dri-devel@lists.freedesktop.org>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <1660152154-17879-1-git-send-email-quic_khsieh@quicinc.com>
From:   Abhinav Kumar <quic_abhinavk@quicinc.com>
In-Reply-To: <1660152154-17879-1-git-send-email-quic_khsieh@quicinc.com>
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On 8/10/2022 10:22 AM, Kuogee Hsieh wrote:
> dp_bridge_disable() is the first step toward tearing down main link.
> Its major function is to start transmitting idle pattern to replace
> video stream. This patch will check hpd_state to make sure main link
> is enabled before commit changes of main link's configuration to
> push idle pattern out to avoid system crashing due to main link clock
> is disabled while access main link registers.

Do you also want to give the full stack of unclocked access here?

> 
> Changes in v2:
> -- changes Fixes patch
> -- fix eported-by
> -- add Closes tag
> 
> Fixes: 375a126090b9 ("drm/msm/dp: tear down main link at unplug handle immediately")
> Reported-by: leonard@lausen.nl

This is still incorrect. Should be:

Reported-by: Leonard Lausen <leonard@lausen.nl>

> Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/17
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dp/dp_display.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index b36f8b6..678289a 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1729,10 +1729,20 @@ void dp_bridge_disable(struct drm_bridge *drm_bridge)
>   	struct msm_dp_bridge *dp_bridge = to_dp_bridge(drm_bridge);
>   	struct msm_dp *dp = dp_bridge->dp_display;
>   	struct dp_display_private *dp_display;
> +	u32 state;
>   
>   	dp_display = container_of(dp, struct dp_display_private, dp_display);
>   
> +	mutex_lock(&dp_display->event_mutex);
> +
> +	state = dp_display->hpd_state;
> +	if (state != ST_DISCONNECT_PENDING && state != ST_CONNECTED) {
> +		mutex_unlock(&dp_display->event_mutex);
> +		return;
> +	}
> +
>   	dp_ctrl_push_idle(dp_display->ctrl);
> +	mutex_unlock(&dp_display->event_mutex);
>   }
>   
>   void dp_bridge_post_disable(struct drm_bridge *drm_bridge)