linux-kernel - Re: [PATCH v4 10/11] drm/bridge: anx7625: fix anx7625_sink

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Message-ID: <783a80d6-63d7-4c00-ba09-0ec07492103c@quicinc.com>
Date: Wed, 23 Apr 2025 15:03:02 +0530
From: Ayushi Makhija <quic_amakhija@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Ayushi Makhija
	<amakhija@....qualcomm.com>
CC: <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <robdclark@...il.com>,
        <sean@...rly.run>, <marijn.suijten@...ainline.org>,
        <andersson@...nel.org>, <robh@...nel.org>, <robh+dt@...nel.org>,
        <krzk+dt@...nel.org>, <konradybcio@...nel.org>, <conor+dt@...nel.org>,
        <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>,
        <rfoss@...nel.org>, <Laurent.pinchart@...asonboard.com>,
        <jonas@...boo.se>, <jernej.skrabec@...il.com>,
        <quic_abhinavk@...cinc.com>, <quic_rajeevny@...cinc.com>,
        <quic_vproddut@...cinc.com>, <quic_jesszhan@...cinc.com>
Subject: Re: [PATCH v4 10/11] drm/bridge: anx7625: fix anx7625_sink_detect()
 to return correct hpd status

On 4/17/2025 4:14 PM, Dmitry Baryshkov wrote:
> On Thu, Apr 17, 2025 at 11:09:08AM +0530, Ayushi Makhija wrote:
>> From: Ayushi Makhija <quic_amakhija@...cinc.com>
>>
>> In the anx7625_sink_detect(), the device is checked to see
>> if it is a panel bridge, and it always sends a "connected"
>> status to the connector. When adding the DP port on port 1 of the
>> anx7625, it incorrectly treats it as a panel bridge and sends an
>> always "connected" status. Instead of checking the status on the
>> panel bridge, it's better to check the hpd_status for connectors
>> that supports hot-plugging. This way, it verifies the hpd_status
>> variable before sending the status to the connector.
> 
> Does this work if the Analogix bridge is connected to an eDP panel? In
> such a case it should report 'connected' even before powering up the
> panel (which might mean HPD pin being low).
> 

Hi Dmitry,

Thanks for the review.

In case of eDP, anx7625_bridge_detect()  will not get called, because this below condition
in anx7625_link_bridge() will not get satisfy. anx7625_sink_detect() is getting called from
anx7625_bridge_detect().

Anx7625_link_bridge()

	if (!platform->pdata.panel_bridge || !anx7625_of_panel_on_aux_bus(dev))
		platform->bridge.ops |= DRM_BRIDGE_OP_HPD | DRM_BRIDGE_OP_DETECT;

So, during the probe time drm_bridge_connector_detect() will return always connected for eDP
connector. Control will go into the else part and for DRM_MODE_CONNECTOR_eDP it will return
the connector status as connector_status_connected (always connected).

drm_bridge_connector_detect 

if (detect) {
                status = detect->funcs->detect(detect);

                if (hdmi)
                        drm_atomic_helper_connector_hdmi_hotplug(connector, status);

                drm_bridge_connector_hpd_notify(connector, status);
        } else {
                switch (connector->connector_type) {
                case DRM_MODE_CONNECTOR_DPI:
                case DRM_MODE_CONNECTOR_LVDS:
                case DRM_MODE_CONNECTOR_DSI:
                case DRM_MODE_CONNECTOR_eDP:
                        status = connector_status_connected;
                        break;
                default:
                        status = connector_status_unknown;
                        break;
                }
        }

https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/display/drm_bridge_connector.c#L180

I don't think so, by removing the below lines of code from anx7625_sink_detect(),
will affect the eDP configuration.Let me know, If I am missing anything.

-	if (ctx->pdata.panel_bridge)
-		return connector_status_connected;
-

Thanks,
Ayushi

>>
>> Signed-off-by: Ayushi Makhija <quic_amakhija@...cinc.com>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
>> ---
>>  drivers/gpu/drm/bridge/analogix/anx7625.c | 3 ---
>>  1 file changed, 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
>> index a32ebe1fa0cd..365d1c871028 100644
>> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
>> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
>> @@ -1814,9 +1814,6 @@ static enum drm_connector_status anx7625_sink_detect(struct anx7625_data *ctx)
>>  
>>  	DRM_DEV_DEBUG_DRIVER(dev, "sink detect\n");
>>  
>> -	if (ctx->pdata.panel_bridge)
>> -		return connector_status_connected;
>> -
>>  	return ctx->hpd_status ? connector_status_connected :
>>  				     connector_status_disconnected;
>>  }
>> -- 
>> 2.34.1
>>
>