RE: [PATCH v9 2/4] drm/msm/dp: Support only IRQ_HPD and REPLUG interrupts for eDP

[Sankeerth Billakanti (QUIC)]

Hi Stephen,

>Quoting Sankeerth Billakanti (2022-04-22 02:11:04)
>> The panel-edp enables the eDP panel power during probe, get_modes and
>> pre-enable. The eDP connect and disconnect interrupts for the eDP/DP
>> controller are directly dependent on panel power. As eDP display can
>> be assumed as always connected, the controller driver can skip the eDP
>> connect and disconnect interrupts. Any disruption in the link status
>> will be indicated via the IRQ_HPD interrupts.
>>
>> So, the eDP controller driver can just enable the IRQ_HPD and replug
>> interrupts. The DP controller driver still needs to enable all the
>> interrupts.
>>
>> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@xxxxxxxxxxx>
>
>The sprinkling of if conditions and manual driving of the DP plug/unplug state
>machine is pretty convoluted. To make it better the driver needs an overhaul.
>Anyway, it looks mostly fine to me except for this replug interrupt question
>below. Otherwise
>
>Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
>
>>  int dp_catalog_ctrl_get_interrupt(struct dp_catalog *dp_catalog) diff
>> --git a/drivers/gpu/drm/msm/dp/dp_display.c
>> b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 055681a..dea4de9 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -1096,6 +1097,13 @@ 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 for external DisplayPort */
>> +       if (!dp->dp_display.is_edp)
>> +               dp_catalog_hpd_config_intr(dp->catalog,
>> +                               DP_DP_HPD_PLUG_INT_MASK |
>> +                               DP_DP_HPD_UNPLUG_INT_MASK,
>> +                               true);
>> +
>
>It seems like only the plug and unplug is enabled for DP here. Is replug
>enabled for eDP when it shouldn't be?
>

By default, all the interrupts are masked. This function is not executed for eDP
anymore because the host_init, phy_init and enable_irq are all done from
modeset_init for eDP with aux_bus. So, none of the eDP hpd interrupts are
enabled or unmasked before pre-enable.

The replug interrupt is unmasked for DP and eDP from the dp_hpd_plug_handle()
and masked from dp_hpd_unplug_handle().

>>         /* Enable interrupt first time
>>          * we are leaving dp clocks on during disconnect
>>          * and never disable interrupt