Re: [PATCH 01/12] drm/i915: Init DRM connector polled field early

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Thu, 2024-01-04 at 10:29 +0200, Imre Deak wrote:
> After an HPD IRQ storm on a connector intel_hpd_irq_storm_detect()
> will
> set the connector's HPD pin state to HPD_MARK_DISABLED and the IRQ
> gets
> disabled. Subsequently intel_hpd_irq_storm_switch_to_polling() will
> enable polling for these connectors, setting the pin state to
> HPD_DISABLED, but only if the connector's base.polled field is set to
> DRM_CONNECTOR_POLL_HPD. intel_hpd_irq_storm_reenable_work() will
> reenable the IRQ - after 2 minutes -  if the pin state is
> HPD_DISABLED.
> 
> The connectors will be created with their base.polled field set to 0,
> which gets initialized only later in i915_hpd_poll_init_work() (using
> intel_connector::polled). If a storm is detected on a connector after
> it's created and IRQs are enabled on it - by intel_hpd_init() - and
> before its bease.polled field is initialized in the above work, the
> connector's HPD pin will stay in the HPD_MARK_DISABLED state -
> leaving
> the IRQ disabled indefinitely - and polling will not get enabled on
> it as
> intended.
> 
> I can't see a reason for initializing base.polled in a delayed
> manner,
> so do this already when creating the connector, to prevent the above
> race condition.

To me it looks like intel_connector::polled is used just to store
original drm_connector::polled value and restore it in 
intel_hpd_irq_storm_reenable_work:

	if (connector->base.polled != connector->polled)
			drm_dbg(&dev_priv->drm,
				"Reenabling HPD on connector %s\n",
				connector->base.name);
		connector->base.polled = connector->polled;

From this perspective it is right thing to do to initialize  connector-
>base.polled as you are doing in this patch.

Reviewed-by: Jouni Högander <jouni.hogander@intel.com>

> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_crt.c  | 1 +
>  drivers/gpu/drm/i915/display/intel_dp.c   | 1 +
>  drivers/gpu/drm/i915/display/intel_dvo.c  | 1 +
>  drivers/gpu/drm/i915/display/intel_hdmi.c | 1 +
>  drivers/gpu/drm/i915/display/intel_sdvo.c | 2 ++
>  drivers/gpu/drm/i915/display/intel_tv.c   | 1 +
>  6 files changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_crt.c
> b/drivers/gpu/drm/i915/display/intel_crt.c
> index abaacea5c2cc4..b330337b842a4 100644
> --- a/drivers/gpu/drm/i915/display/intel_crt.c
> +++ b/drivers/gpu/drm/i915/display/intel_crt.c
> @@ -1069,6 +1069,7 @@ void intel_crt_init(struct drm_i915_private
> *dev_priv)
>         } else {
>                 intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT;
>         }
> +       intel_connector->base.polled = intel_connector->polled;
>  
>         if (HAS_DDI(dev_priv)) {
>                 assert_port_valid(dev_priv, PORT_E);
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 9ff0cbd9c0df5..fed649af8fc85 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -6469,6 +6469,7 @@ intel_dp_init_connector(struct
> intel_digital_port *dig_port,
>                 connector->interlace_allowed = true;
>  
>         intel_connector->polled = DRM_CONNECTOR_POLL_HPD;
> +       intel_connector->base.polled = intel_connector->polled;
>  
>         intel_connector_attach_encoder(intel_connector,
> intel_encoder);
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_dvo.c
> b/drivers/gpu/drm/i915/display/intel_dvo.c
> index 9111e9d46486d..83898ba493d16 100644
> --- a/drivers/gpu/drm/i915/display/intel_dvo.c
> +++ b/drivers/gpu/drm/i915/display/intel_dvo.c
> @@ -536,6 +536,7 @@ void intel_dvo_init(struct drm_i915_private
> *i915)
>         if (intel_dvo->dev.type == INTEL_DVO_CHIP_TMDS)
>                 connector->polled = DRM_CONNECTOR_POLL_CONNECT |
>                         DRM_CONNECTOR_POLL_DISCONNECT;
> +       connector->base.polled = connector->polled;
>  
>         drm_connector_init_with_ddc(&i915->drm, &connector->base,
>                                     &intel_dvo_connector_funcs,
> diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c
> b/drivers/gpu/drm/i915/display/intel_hdmi.c
> index eedef8121ff7c..55048c56bc527 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> @@ -3017,6 +3017,7 @@ void intel_hdmi_init_connector(struct
> intel_digital_port *dig_port,
>                 connector->ycbcr_420_allowed = true;
>  
>         intel_connector->polled = DRM_CONNECTOR_POLL_HPD;
> +       intel_connector->base.polled = intel_connector->polled;
>  
>         if (HAS_DDI(dev_priv))
>                 intel_connector->get_hw_state =
> intel_ddi_connector_get_hw_state;
> diff --git a/drivers/gpu/drm/i915/display/intel_sdvo.c
> b/drivers/gpu/drm/i915/display/intel_sdvo.c
> index 9218047495fb4..4e4a87f841787 100644
> --- a/drivers/gpu/drm/i915/display/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/display/intel_sdvo.c
> @@ -2805,6 +2805,7 @@ intel_sdvo_dvi_init(struct intel_sdvo
> *intel_sdvo, u16 type)
>         } else {
>                 intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT
> | DRM_CONNECTOR_POLL_DISCONNECT;
>         }
> +       intel_connector->base.polled = intel_connector->polled;
>         encoder->encoder_type = DRM_MODE_ENCODER_TMDS;
>         connector->connector_type = DRM_MODE_CONNECTOR_DVID;
>  
> @@ -2880,6 +2881,7 @@ intel_sdvo_analog_init(struct intel_sdvo
> *intel_sdvo, u16 type)
>         intel_connector = &intel_sdvo_connector->base;
>         connector = &intel_connector->base;
>         intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT;
> +       intel_connector->base.polled = intel_connector->polled;
>         encoder->encoder_type = DRM_MODE_ENCODER_DAC;
>         connector->connector_type = DRM_MODE_CONNECTOR_VGA;
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_tv.c
> b/drivers/gpu/drm/i915/display/intel_tv.c
> index d4386cb3569e0..f3598fe39fda5 100644
> --- a/drivers/gpu/drm/i915/display/intel_tv.c
> +++ b/drivers/gpu/drm/i915/display/intel_tv.c
> @@ -1990,6 +1990,7 @@ intel_tv_init(struct drm_i915_private
> *dev_priv)
>          * More recent chipsets favour HDMI rather than integrated S-
> Video.
>          */
>         intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT;
> +       intel_connector->base.polled = intel_connector->polled;
>  
>         drm_connector_init(&dev_priv->drm, connector,
> &intel_tv_connector_funcs,
>                            DRM_MODE_CONNECTOR_SVIDEO);