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Date:   Mon, 11 Oct 2021 08:24:41 -0700
From:   khsieh@codeaurora.org
To:     Bjorn Andersson <bjorn.andersson@linaro.org>
Cc:     Stephen Boyd <swboyd@chromium.org>,
        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>
Subject: Re: [PATCH] drm/msm/dp: Shorten SETUP timeout
In-Reply-To: <YWB1cXoaGRXfGau1@ripper>
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On 2021-10-08 09:44, Bjorn Andersson wrote:
> On Fri 08 Oct 09:07 PDT 2021, khsieh@codeaurora.org wrote:
> 
>> On 2021-10-07 15:34, Stephen Boyd wrote:
>> > 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.
>> 
>> we need usb calls qcom_qmp_phy_init() before dp.
> 
> Why?
I do not know the details.
But I did see below scenario,

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().