Re: [PATCH RFT 4/7] phy: qcom: qmp-combo: register a typec mux to change the QPHY_MODE

[neil . armstrong]

On 29/02/2024 16:54, Dmitry Baryshkov wrote:
> On Thu, 29 Feb 2024 at 17:47, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
> > On 29/02/2024 16:25, Dmitry Baryshkov wrote:
> > > On Thu, 29 Feb 2024 at 15:08, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
> > > > Register a typec mux in order to change the PHY mode on the Type-C
> > > > mux events depending on the mode and the svid when in Altmode setup.
> > > >
> > > > The DisplayPort phy should be left enabled if is still powered on
> > > > by the DRM DisplayPort controller, so bail out until the DisplayPort
> > > > PHY is not powered off.
> > > >
> > > > The Type-C Mode/SVID only changes on plug/unplug, and USB SAFE states
> > > > will be set in between of USB-Only, Combo and DisplayPort Only so
> > > > this will leave enough time to the DRM DisplayPort controller to
> > > > turn of the DisplayPort PHY.
> > >
> > > I think this is not fully correct. Please correct me if I'm wrong, but
> > > it is possible to switch between USB / USB+DP / DP-only at runtime.
> > > See the Status Update and Configure commands.
> >
> > Yes, but the current implementation is still valid because we need to
> > have the DP powered-off before changing the PHY mode.
>
> Even for switching between 2 lane and 4 lane modes?

So the Altmode pin assignment says how much lanes you can get (2 or 4),
and AUX data will say how much the adapter/display supports.

My native DP monitor uses the 4 lanes, while my USB-C->HDMI dongles
declares the 4lanes pin assigment but DP controller only ever tries 2 lanes.

I don't have USB-C->HDMI with 4lanes DP, but it should work fine.

Neil

> I'll check how my USB-A+DP dongles work with respect to the altmode
> configuration.
>
> > I never encountered such setup and I have no idea how to test this.
> >
> > > > Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>