Re: [PATCH v6 6/8] drm/msm/dp: remove unnecessary delay during boot

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On Mon, 4 Apr 2022 at 16:53, Sankeerth Billakanti (QUIC)
<quic_sbillaka@quicinc.com> wrote:
>
> Hi Doug,
>
> > On Wed, Mar 30, 2022 at 9:04 AM Sankeerth Billakanti
> > <quic_sbillaka@quicinc.com> wrote:
> > >
> > > Remove the unnecessary delay in executing the EV_HPD_INIT_SETUP
> > event.
> >
> > Tell me more and put it in the commit message! Why did it used to be
> > necessary and why is it no longer necessary? Inquiring minds want to know.
> >
>
> Okay. I will add proper description. The DP phy is shared with usb and executing the
> dp phy_init before the usb phy_init was causing usb devices to not function.

I always wondered, how does this work for the 4-lane DP dongles, where
there is no USB mode/lanes?

> Earlier, enabling phy_init was done when the EV_HPD_INIT_SETUP event was executed.
> So, we had scheduled it to execute after 10 second to let the usb driver complete the phy_init first.
>
> Kuogee made the below change to move the DP phy_init to execute after the DP is connected
> https://patchwork.kernel.org/project/linux-arm-msm/patch/1642531648-8448-2-git-send-email-quic_khsieh@quicinc.com/
>
> So, there is no need for the DP driver to wait 10 seconds for the phy initialization anymore.
>
> eDP PHY is not shared with usb. So, it can be programmed anytime, hence not needing any delay.



-- 
With best wishes
Dmitry