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

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: neil.armstrong@linaro.org
Cc: Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	 Vinod Koul <vkoul@kernel.org>,
	Kishon Vijay Abraham I <kishon@kernel.org>,
	Rob Herring <robh@kernel.org>,
	 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	 linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFT 4/7] phy: qcom: qmp-combo: register a typec mux to change the QPHY_MODE
Date: Thu, 29 Feb 2024 17:54:30 +0200	[thread overview]
Message-ID: <CAA8EJpq0E_t6bi4TymtpxdX0ZHHNJgBU2gFEEZDWSUZg27pEvw@mail.gmail.com> (raw)
In-Reply-To: <d50ca4c0-8954-4e4c-9ce9-2c40ebacf8b0@linaro.org>

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

-- 
With best wishes
Dmitry