Re: [PATCH v6] drm/msm/dp: Always clear mask bits to disable interrupts at dp_ctrl_reset_irq_ctrl()

[Kuogee Hsieh]

On 5/17/2022 1:25 AM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2022-05-12 12:43:18)
> > diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> > index af7a80c..f3e333e 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> > @@ -1389,8 +1389,13 @@ void dp_ctrl_reset_irq_ctrl(struct dp_ctrl *dp_ctrl, bool enable)
> >
> >          dp_catalog_ctrl_reset(ctrl->catalog);
> >
> > -       if (enable)
> > -               dp_catalog_ctrl_enable_irq(ctrl->catalog, enable);
> > +       /*
> > +        * all dp controller programmable registers will not
> > +        * be reset to default value after DP_SW_RESET
> > +        * therefore interrupt mask bits have to be updated
> > +        * to enable/disable interrupts
> > +        */
> > +       dp_catalog_ctrl_enable_irq(ctrl->catalog, enable);
> I think Dmitry requested that this part be split off to a different
> patch. It's fixing the call to dp_ctrl_reset_irq_ctrl() for the disable
> case.
ok, will do that
> >   }
> >
> >   void dp_ctrl_phy_init(struct dp_ctrl *dp_ctrl)
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> > index c388323..ab691aa 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -98,6 +98,8 @@ struct dp_display_private {
> >          struct dp_ctrl    *ctrl;
> >          struct dp_debug   *debug;
> >
> > +       bool suspended;
> > +
> Can we not have this flag? I also don't understand how this patch waits
> for the event queue to drain. There are now multiple places we check to
> see if we've suspended, but is it even possible to be in those places
> during suspend? What is wrong with moving to an irq thread? Is it
> because we want to wait for a modeset (EV_USER_NOTIFICATION)?

dp_pm_suspend happen after display off. therefore event q should be 
emptied when dp_pm_suspend called.

since dp_pm_suspend and event_thread share an mutex, if suspended flag 
set at dp_pm_suspend which guarantee

event thread will not be wakeed up to process since event q is empty.

We used event q is to guarantee all events (irqs) are kept in event q 
with timing order (no any events missed) and executed later in timing 
order too to work the scenario likes dongle plug/unplugged several times 
consecutively.

We used to workqueue but cause many synchronization issues.

I will try thread_irq to see it will yield any advantage over kernel thread.

> >          struct dp_usbpd_cb usbpd_cb;
> >          struct dp_display_mode dp_mode;
> >          struct msm_dp dp_display;