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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Thu, 7 Oct 2021 18:34:53 -0400
Message-ID: <CAE-0n51bvKXmHj0X_cvR2fdk4-mh4SRsrEE33H0e1Q+p=7iPxA@mail.gmail.com>
Subject: Re: [PATCH] drm/msm/dp: Shorten SETUP timeout
To:     Bjorn Andersson <bjorn.andersson@linaro.org>, khsieh@codeaurora.org
Cc:     Abhinav Kumar <abhinavk@codeaurora.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
        linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Sankeerth Billakanti <sbillaka@codeaurora.org>
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Quoting khsieh@codeaurora.org (2021-10-07 13:28:12)
> On 2021-10-07 13:06, Bjorn Andersson wrote:
> > On Thu 07 Oct 12:51 PDT 2021, khsieh@codeaurora.org wrote:
> >
> >> On 2021-10-06 10:31, Bjorn Andersson wrote:
> >> > On Wed 06 Oct 08:37 PDT 2021, khsieh@codeaurora.org wrote:
> >> >
> >> > > On 2021-10-05 19:10, Bjorn Andersson wrote:
> >> > > > On Tue 05 Oct 16:04 PDT 2021, khsieh@codeaurora.org wrote:
> >> > > >
> >> > > > > On 2021-10-05 15:36, Stephen Boyd wrote:
> >> > > > > > Quoting Bjorn Andersson (2021-10-05 14:40:38)
> >> > > > > > > On Tue 05 Oct 11:45 PDT 2021, Stephen Boyd wrote:
> >> > > > > > >
> >> > > > > > > > Quoting Bjorn Andersson (2021-10-04 19:37:50)
> >> > > > > > > > > Found in the middle of a patch from Sankeerth was the reduction of the
> >> > > > > > > > > INIT_SETUP timeout from 10s to 100ms. Upon INIT_SETUP timeout the host
> >> > > > > > > > > is initalized and HPD interrupt start to be serviced, so in the case of
> >> > > > > > > > > eDP this reduction improves the user experience dramatically - i.e.
> >> > > > > > > > > removes 9.9s of bland screen time at boot.
> >> > > > > > > > >
> >> > > > > > > > > Suggested-by: Sankeerth Billakanti <sbillaka@codeaurora.org>
> >> > > > > > > > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> >> > > > > > > > > ---
> >> > > > > > > >
> >> > > > > > > > Any Fixes tag? BTW, the delay design is pretty convoluted. I had to go
> >> > > > > > > > re-read the code a couple times to understand that it's waiting 100ms
> >> > > > > > > > times the 'delay' number. Whaaaaat?
> >> > > > > > > >
> >> > > > > > >
> >> > > > > > > I assume you're happy with the current 10s delay on the current
> >> > > > > > > devices, so I don't think we should push for this to be backported.
> >> > > > > > > I have no need for it to be backported on my side at least.
> >> > > > > > >
> >> > > > > >
> >> > > > > > Sure. Fixes tag != backported to stable trees but it is close.
> >> > > > > >
> >> > > > > > > > Reviewed-by: Stephen Boyd <swboyd@chromium.org>
> >> > > > > > >
> >> > > > >   dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 1); <== to 100ms
> >> > > > >
> >> > > > > This patch will prevent usb3 from working due to dp driver
> >> > > > > initialize phy
> >> > > > > earlier than usb3 which cause timeout error at power up usb3 phy
> >> > > > > when both
> >> > > > > edp and dp are enabled.
> >> > > >
> >> > > > Can you please help me understand what you mean here, I use this on my
> >> > > > sc8180x with both eDP and USB-C/DP right now. What is it that doesn't
> >> > > > work? Or am I just lucky in some race condition?
> >> > > >
> >> > > > Thanks,
> >> > > > Bjorn
> >> > > >
> >> > > The problem is seen at sc7280.
> >> > > Apple dongle have both  hdmi and usb port.
> >> > > plug Apple dongle into type-c, then plug DP into apple's hdmi port
> >> > > and usb
> >> > > mouse into apple's usb port.
> >> > > If edp enabled at this time, then usb mouse will not work due to
> >> > > timeout at
> >> > > phy power up.
> >> > >
> >> >
> >> > Okay, so you're saying that if the DP driver invokes phy_power_on()
> >> > before the USB driver does, USB initialization fails (or at least USB
> >> > doesn't work)?
> >>
> >> if dp driver call qcom_qmp_phy_init() before usb3 call
> >> qcom_qmp_phy_init(),
> >> usb3 driver will timeout at readl_poll_timeout(status, val, (val &
> >> mask) ==
> >> ready, 10, PHY_INIT_COMPLETE_TIMEOUT) of qcom_qmp_phy_power_on().
> >
> > Thanks, I will try to reproduce this on my side. So the 10 seconds here
> > is strictly to give good enough time for the dwc3 driver to probe...
> >
> > Any idea why you're saying that this is specific to sc7280, what
> > changed
> > from sc7180?
>
> I did not have sc7180 with edp before so that i am not sure it will
> happen on sc7180 or not.
> The usb3 does not work when both edp and dp enabled I just seen at
> sc7280.
> Current at sc7280 EC is not boot up correctly when system power up.
> I have to manual reboot EC from linux kernel shell before DP/usb3 can
> work.
> I am not sure this contribute to this problem or not.
>

Can you make the usb driver into a module and only load that module
later in boot after the DP driver calls qcom_qmp_phy_init()? That would
be an easy way to move usb probe after DP probe and expose this problem.