Re: [PATCH 0/3] phy: qcom: edp: Add support for DT phy mode configuration

[Konrad Dybcio]

On 21.12.2023 17:27, Dmitry Baryshkov wrote:
> On Tue, 19 Dec 2023 at 22:55, Abel Vesa <abel.vesa@xxxxxxxxxx> wrote:
>>
>> Until now, all platform that supported both eDP and DP had different
>> compatibles for each mode. Using different compatibles for basically
>> the same IP block but for a different configuration is bad way all
>> around. There is a new compute platform from Qualcomm that supports
>> both eDP and DP with the same PHY. So instead of following the old
>> method, we should allow the mode to be configured from devicetree.
>>
>> There has been an off-list discussion on what would be the right way
>> to pass on the PHY mode information to the driver and it has been
>> concluded that phy-cells is the way to go. This means that basically
>> the controller will pass another value (that is, the PHY type) to
>> its 'phys' DT property.
>>
>> For this, we need both the bindings value and the PHY mode value to be
>> added as well.
>>
>> The controller part will follow shortly. But for now, lets see where
>> this is going.
>>
>> There has been another attempt at this here:
>> https://lore.kernel.org/all/20231122-phy-qualcomm-edp-x1e80100-v3-3-576fc4e9559d@xxxxxxxxxx/
>>
>> Compared to that version, this one uses the phy-cells method and drops
>> the X1E80100 support. The X1E80100 support will be a separate patchset.
> 
> After several back and forth discussions, I think that this approach
> is not correct and not that easy to extend. Instead I'd like to
> suggest adding a property to the DP controller, which enables eDP
> behaviour (and thus makes DP driver call phy_set_mode()). Something
> like this:
> dp: displayport-controller@ae0000 {
>     compatible = "qcom,sm8000-dp";
>     /* reg, interrupts, etc */
>    edp-interface;
>    /* or simpler */
>    is-edp;
> };
> 
> What do you think?

Please excuse my alzheimer, but why did we not go with phy-type after
the last discussion?

Konrad