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

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Message-ID: <CAA8EJpq0E_t6bi4TymtpxdX0ZHHNJgBU2gFEEZDWSUZg27pEvw@mail.gmail.com>
Date: Thu, 29 Feb 2024 17:54:30 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: neil.armstrong@...aro.org
Cc: Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFT 4/7] phy: qcom: qmp-combo: register a typec mux to
 change the QPHY_MODE

On Thu, 29 Feb 2024 at 17:47, Neil Armstrong <neil.armstrong@...aro.org> wrote:
>
> On 29/02/2024 16:25, Dmitry Baryshkov wrote:
> > On Thu, 29 Feb 2024 at 15:08, Neil Armstrong <neil.armstrong@...aro.org> 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?

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@...aro.org>


-- 
With best wishes
Dmitry