[Freedreno] [PATCH v1 1/2] drm/msm/dp: enable HDP plugin/unplugged interrupts to hpd_enable/disable
Dmitry Baryshkov
dmitry.baryshkov at linaro.org
Fri May 12 17:28:05 UTC 2023
On Fri, 12 May 2023 at 19:52, Kuogee Hsieh <quic_khsieh at quicinc.com> wrote:
>
>
> On 5/11/2023 5:54 PM, Dmitry Baryshkov wrote:
> > On Fri, 12 May 2023 at 03:16, Kuogee Hsieh <quic_khsieh at quicinc.com> wrote:
> >>
> >> On 5/11/2023 8:57 AM, Dmitry Baryshkov wrote:
> >>> On 11/05/2023 18:53, Bjorn Andersson wrote:
> >>>> On Thu, May 11, 2023 at 07:24:46AM +0300, Dmitry Baryshkov wrote:
> >>>>> On Wed, 10 May 2023 at 23:31, Kuogee Hsieh <quic_khsieh at quicinc.com>
> >>>>> wrote:
> >>>>>> The internal_hpd flag was introduced to handle external DP HPD
> >>>>>> derived from GPIO
> >>>>>> pinmuxed into DP controller. HPD plug/unplug interrupts cannot be
> >>>>>> enabled until
> >>>>>> internal_hpd flag is set to true.
> >>>>>> At both bootup and resume time, the DP driver will enable external DP
> >>>>>> plugin interrupts and handle plugin interrupt accordingly.
> >>>>>> Unfortunately
> >>>>>> dp_bridge_hpd_enable() bridge ops function was called to set
> >>>>>> internal_hpd
> >>>>>> flag to true later than where DP driver expected during bootup time.
> >>>>>>
> >>>>>> This causes external DP plugin event to not get detected and
> >>>>>> display stays blank.
> >>>>>> Move enabling HDP plugin/unplugged interrupts to
> >>>>>> dp_bridge_hpd_enable()/disable() to
> >>>>>> set internal_hpd to true along with enabling HPD plugin/unplugged
> >>>>>> interrupts
> >>>>>> simultaneously to avoid timing issue during bootup and resume.
> >>>>>>
> >>>>>> Fixes: cd198caddea7 ("drm/msm/dp: Rely on hpd_enable/disable
> >>>>>> callbacks")
> >>>>>> Signed-off-by: Kuogee Hsieh <quic_khsieh at quicinc.com>
> >>>>> Thanks for debugging this!
> >>>>>
> >>>>> However after looking at the driver I think there is more than this.
> >>>>>
> >>>>> We have several other places gated on internal_hpd flag, where we do
> >>>>> not have a strict ordering of events.
> >>>>> I see that dp_hpd_plug_handle() and dp_hpd_unplug_handle() also toggle
> >>>>> DP_DP_IRQ_HPD_INT_MASK and DP_DP_HPD_REPLUG_INT_MASK depending on
> >>>>> internal_hpd. Can we toggle all 4 interrupts from the
> >>>>> hpd_enable/hpd_disable functions? If we can do it, then I think we can
> >>>>> drop the internal_hpd flag completely.
> >>>>>
> >>>> Yes, that's what I believe the DRM framework intend us to do.
> >>>>
> >>>> The problem, and reason why I didn't do tat in my series, was that in
> >>>> order to update the INT_MASKs you need to clock the IP-block and that's
> >>>> done elsewhere.
> >>>>
> >>>> So, for the internal_hpd case, it seems appropriate to pm_runtime_get()
> >>>> in hpd_enable() and unmask the HPD interrupts, and mask the interrupts
> >>>> and pm_runtime_put() in hpd_disable().
> >>>>
> >>>>
> >>>> But for edp and external HPD-signal we also need to make sure power is
> >>>> on while something is connected...
> >>> I think this is already handled by the existing code, see calls to the
> >>> dp_display_host_init().
> >>>
> >>>>> I went on and checked other places where it is used:
> >>>>> - dp_hpd_unplug_handle(), guarding DP_DP_HPD_PLUG_INT_MASK toggling. I
> >>>>> think we can drop these two calls completely. The function is under
> >>>>> the event_mutex protection, so other events can not interfere.
> >>>>> - dp_bridge_hpd_notify(). What is the point of this check? If some
> >>>>> other party informs us of the HPD event, we'd better handle it instead
> >>>>> of dropping it. Correct? In other words, I'd prefer seeing the
> >>>>> hpd_event_thread removal. Instead of that I think that on
> >>>>> HPD/plug/unplug/etc. IRQ the driver should call into the drm stack,
> >>>>> then the hpd_notify call should process those events.
> >>>>>
> >> 1) DP with GPIO: No downstream drm_bridge are connected, is_edp = false
> >> and internal HPD-logic is in used (internal_hpd = true). Power needs to
> >> be on at all times etc.
> >>
> >> 2) DP without GPIO: Downstream drm_bridge connected, is_edp = false and
> >> internal HPD-logic should not be used/enabled (internal_hpd = false).
> >> Power doesn't need to be on unless hpd_notify is invoked to tell us that
> >> there's something connected...
> >>
> >> - dp_bridge_hpd_notify(). What is the point of this check? <== i have
> >> below two questions,
> >>
> >> 1) can you explain when/what this dp_bridge_hpd_notify() will be called?
> > The call chain is drm_bridge_hpd_notify() ->
> > drm_bridge_connector_hpd_notify() -> .hpd_notify() for all drm_bridge
> > in chain
> >
> > One should add a call to drm_bridge_hpd_notify() when the hotplug
> > event has been detected.
> >
> > Also please note the patch https://patchwork.freedesktop.org/patch/484432/
> >
> >> 2) is dp_bridge_hpd_notify() only will be called at above case #2? and
> >> it will not be used by case #1?
> > Once the driver calls drm_bridge_hpd_notify() in the hpd path, the
> > hpd_notify callbacks will be called in case#1 too.
> >
> > BTW: I don't see drm_bridge_hpd_notify() or
> > drm_kms_{,connector_}_hotplug_event() HPD notifications in the DP
> > driver at all. This should be fixed.
>
> Just curious, since dp_bridge_detect() only return either
> connector_status_connected or connector_status_disconnect,
>
> how IRQ_HPD_INT (attention) and HPD_REPLUG_INT be generated at DP case#1?
if (bridge.status == connected && status == connected) {
either attention or replug were reported
}
BTW: what is HPD_REPLUG_INT, if you excuse my ignorance?
>
> >>
> >>
> >>>> I agree, that seems to be what's expected of us from the DRM framework.
> >>>>
> >>>> Regards,
> >>>> Bjorn
> >>>>
> >>>>>> ---
> >>>>>> drivers/gpu/drm/msm/dp/dp_display.c | 27 ++++++++++++++-------------
> >>>>>> 1 file changed, 14 insertions(+), 13 deletions(-)
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> >>>>>> b/drivers/gpu/drm/msm/dp/dp_display.c
> >>>>>> index 3e13acdf..71aa944 100644
> >>>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> >>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> >>>>>> @@ -1088,13 +1088,6 @@ static void dp_display_config_hpd(struct
> >>>>>> dp_display_private *dp)
> >>>>>> dp_display_host_init(dp);
> >>>>>> dp_catalog_ctrl_hpd_config(dp->catalog);
> >>>>>>
> >>>>>> - /* Enable plug and unplug interrupts only if requested */
> >>>>>> - if (dp->dp_display.internal_hpd)
> >>>>>> - dp_catalog_hpd_config_intr(dp->catalog,
> >>>>>> - DP_DP_HPD_PLUG_INT_MASK |
> >>>>>> - DP_DP_HPD_UNPLUG_INT_MASK,
> >>>>>> - true);
> >>>>>> -
> >>>>>> /* Enable interrupt first time
> >>>>>> * we are leaving dp clocks on during disconnect
> >>>>>> * and never disable interrupt
> >>>>>> @@ -1396,12 +1389,6 @@ static int dp_pm_resume(struct device *dev)
> >>>>>>
> >>>>>> dp_catalog_ctrl_hpd_config(dp->catalog);
> >>>>>>
> >>>>>> - if (dp->dp_display.internal_hpd)
> >>>>>> - dp_catalog_hpd_config_intr(dp->catalog,
> >>>>>> - DP_DP_HPD_PLUG_INT_MASK |
> >>>>>> - DP_DP_HPD_UNPLUG_INT_MASK,
> >>>>>> - true);
> >>>>>> -
> >>>>>> if (dp_catalog_link_is_connected(dp->catalog)) {
> >>>>>> /*
> >>>>>> * set sink to normal operation mode -- D0
> >>>>>> @@ -1801,15 +1788,29 @@ void dp_bridge_hpd_enable(struct drm_bridge
> >>>>>> *bridge)
> >>>>>> {
> >>>>>> struct msm_dp_bridge *dp_bridge = to_dp_bridge(bridge);
> >>>>>> struct msm_dp *dp_display = dp_bridge->dp_display;
> >>>>>> + struct dp_display_private *dp;
> >>>>>> +
> >>>>>> + dp = container_of(dp_display, struct dp_display_private,
> >>>>>> dp_display);
> >>>>>>
> >>>>>> dp_display->internal_hpd = true;
> >>>>>> + dp_catalog_hpd_config_intr(dp->catalog,
> >>>>>> + DP_DP_HPD_PLUG_INT_MASK |
> >>>>>> + DP_DP_HPD_UNPLUG_INT_MASK,
> >>>>>> + true);
> >>>>>> }
> >>>>>>
> >>>>>> void dp_bridge_hpd_disable(struct drm_bridge *bridge)
> >>>>>> {
> >>>>>> struct msm_dp_bridge *dp_bridge = to_dp_bridge(bridge);
> >>>>>> struct msm_dp *dp_display = dp_bridge->dp_display;
> >>>>>> + struct dp_display_private *dp;
> >>>>>> +
> >>>>>> + dp = container_of(dp_display, struct dp_display_private,
> >>>>>> dp_display);
> >>>>>>
> >>>>>> + dp_catalog_hpd_config_intr(dp->catalog,
> >>>>>> + DP_DP_HPD_PLUG_INT_MASK |
> >>>>>> + DP_DP_HPD_UNPLUG_INT_MASK,
> >>>>>> + false);
> >>>>>> dp_display->internal_hpd = false;
> >>>>>> }
> >>>>> --
> >>>>> With best wishes
> >>>>> Dmitry
> >
> >
--
With best wishes
Dmitry
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