[Freedreno] [PATCH v1 1/2] drm/msm/dp: enable HDP plugin/unplugged interrupts to hpd_enable/disable
Kuogee Hsieh
quic_khsieh at quicinc.com
Fri May 12 16:52:00 UTC 2023
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?
>>
>>
>>>> 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
>
>
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