linux-kernel - Re: [PATCH v4 5/6] phy: qcom: qmp-combo: register a typec mux to change the QMPPHY

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Message-ID: <y4yiyokoo7fclwlpyhct4o7mt6swustuciigqnte5pruust26q@ryvuwpd6h4qm>
Date: Mon, 11 Aug 2025 13:55:47 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Cc: Konrad Dybcio <konradybcio@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v4 5/6] phy: qcom: qmp-combo: register a typec mux to
 change the QMPPHY_MODE

On Mon, Aug 11, 2025 at 12:37:00PM +0200, Konrad Dybcio wrote:
> On 8/9/25 10:13 AM, Dmitry Baryshkov wrote:
> > On Thu, Aug 07, 2025 at 06:33:23PM +0200, Konrad Dybcio wrote:
> >> From: Neil Armstrong <neil.armstrong@...aro.org>
> >>
> >> 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.
> >>
> >> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> >> [konrad: renaming, rewording, bug fixes]
> >> Signed-off-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> >> ---
> >>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 118 ++++++++++++++++++++++++++++--
> >>  1 file changed, 113 insertions(+), 5 deletions(-)
> >>
> >> +
> >> +	if (qmp->qmpphy_mode != QMPPHY_MODE_USB3_ONLY && qmp->dp_powered_on) {
> >> +		dev_dbg(qmp->dev, "typec_mux_set: DP PHY is still in use, delaying switch\n");
> >> +		return 0;
> >> +	}
> > 
> > I can't say that I'm fully happy about it, nevertheless:
> > 
> > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> 
> IIUC we'll be able to get rid of it after the dp rework?

Which one? The HPD? not really. My unhappiness is about the sync between
USB and DP. I'm unsure whether we need higher level of sync for
USB-or-DP PHYs.

-- 
With best wishes
Dmitry