linux-kernel - Re: [PATCH] soc: qcom: pmic_glink: fix connector type to be DisplayPort

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Date:   Wed, 25 Oct 2023 15:48:51 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Johan Hovold <johan@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        Simon Ser <contact@...rsion.fr>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc: qcom: pmic_glink: fix connector type to be
 DisplayPort

On 25/10/2023 15:23, Johan Hovold wrote:
> On Wed, Oct 11, 2023 at 01:52:29AM +0300, Dmitry Baryshkov wrote:
>> As it was pointed out by Simon Ser, the DRM_MODE_CONNECTOR_USB connector
>> is reserved for the GUD devices. Other drivers (i915, amdgpu) use
>> DRM_MODE_CONNECTOR_DisplayPort even if the DP stream is handled by the
>> USB-C altmode. While we are still working on implementing the proper way
>> to let userspace know that the DP is wrapped into USB-C, change
>> connector type to be DRM_MODE_CONNECTOR_DisplayPort.
>>
>> Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support")
>> Cc: Simon Ser <contact@...rsion.fr>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>> ---
>>   drivers/soc/qcom/pmic_glink_altmode.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
>> index 9569d999391d..6f8b2f7ae3cc 100644
>> --- a/drivers/soc/qcom/pmic_glink_altmode.c
>> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
>> @@ -467,7 +467,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
>>   		alt_port->bridge.funcs = &pmic_glink_altmode_bridge_funcs;
>>   		alt_port->bridge.of_node = to_of_node(fwnode);
>>   		alt_port->bridge.ops = DRM_BRIDGE_OP_HPD;
>> -		alt_port->bridge.type = DRM_MODE_CONNECTOR_USB;
>> +		alt_port->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
>>   
>>   		ret = devm_drm_bridge_add(dev, &alt_port->bridge);
>>   		if (ret) {
> 
> I was just going to post a patch fixing this after finally investigating
> why the DisplayPort outputs on the X13s were annoyingly identified as
> "Unknown20-1" and "Unknown20-2" instead of the expected "DP-1" and
> "DP-2".

Well, that depends on the userspace being updated to know about USB 
connectors or not. But you are right, we should probably mention that in 
the commit message.

> 
> A lore search just before posting led me to this fix from two weeks ago.
> 
> I think the commit message should have mentioned something about the how
> this change affects user space. My patch also had a CC stable, but I
> guess we can ping the stable team once it hits mainline:
> 
> commit e5f55bf5ad4effdd59d4d06c839a0ac553a73c7d (HEAD -> work)
> Author: Johan Hovold <johan+linaro@...nel.org>
> Date:   Wed Oct 25 11:54:09 2023 +0200
> 
>      soc: qcom: pmic_glink_altmode: fix DP alt mode connector type
>      
>      The PMIC glink altmode bridge connector type should be "DisplayPort"
>      rather than "USB", which is intended for custom USB display protocols
>      (e.g. see 40e1a70b4aed ("drm: Add GUD USB Display driver")).
>      
>      This specifically makes the DisplayPort outputs on the Lenovo ThinkPad
>      X13s show up as "DP-1" and "DP-2" rather than "Unknown20-1" and
>      "Unknown20-2" with xrandr as expected (by users and tools):
>      
>        Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 5120 x 4096
>        eDP-1 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 286mm x 178mm
>           1920x1200     60.03*+
>           1600x1200     60.00
>        DP-1 disconnected (normal left inverted right x axis y axis)
>        DP-2 connected (normal left inverted right x axis y axis)
>           1920x1200     59.95 +
>        ...
>      
>      Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support")
>      Cc: stable@...r.kernel.org      # 6.3
>      Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> 
> Johan

-- 
With best wishes
Dmitry