[PATCH v4 4/4] drm/i915: Enable polling when we don't have hpd
Daniel Vetter
daniel at ffwll.ch
Tue Jun 21 19:26:59 UTC 2016
On Tue, Jun 21, 2016 at 02:18:35PM -0400, Lyude wrote:
> Unfortunately, there's two situations where we lose hpd right now:
> - Runtime suspend
> - When we've shut off all of the power wells on Valleyview/Cherryview
>
> While it would be nice if this didn't cause issues, this has the
> ability to get us in some awkward states where a user won't be able to
> get their display to turn on. For instance; if we boot a Valleyview
> system without any monitors connected, it won't need any of it's power
> wells and thus shut them off. Since this causes us to lose HPD, this
> means that unless the user knows how to ssh into their machine and do a
> manual reprobe for monitors, none of the monitors they connect after
> booting will actually work.
>
> Eventually we should come up with a better fix then having to enable
> polling for this, since this makes rpm a lot less useful, but for now
> the infrastructure in i915 just isn't there yet to get hpd in these
> situations.
>
> Changes since v1:
> - Add comment explaining the addition of the if
> (!mode_config->poll_running) in intel_hpd_init()
> - Remove unneeded if (!dev->mode_config.poll_enabled) in
> i915_hpd_poll_init_work()
> - Call to drm_helper_hpd_irq_event() after we disable polling
> - Add cancel_work_sync() call to intel_hpd_cancel_work()
>
> Changes since v2:
> - Apparently dev->mode_config.poll_running doesn't actually reflect
> whether or not a poll is currently in progress, and is actually used
> for dynamic module paramter enabling/disabling. So now we instead
> keep track of our own poll_running variable in dev_priv->hotplug
> - Clean i915_hpd_poll_init_work() a little bit
>
> Changes since v3:
> - Remove the now-redundant connector loop in intel_hpd_init(), just
> rely on intel_hpd_poll_enable() for setting connector->polled
> correctly on each connector
> - Get rid of poll_running
> - Don't assign enabled in i915_hpd_poll_init_work before we actually
> lock dev->mode_config.mutex
> - Wrap enabled assignment in i915_hpd_poll_init_work() in READ_ONCE()
> for doc purposes
> - Do the same for dev_priv->hotplug.poll_enabled with WRITE_ONCE in
> intel_hpd_poll_enable()
> - Add some comments about racing not mattering in intel_hpd_poll_enable
>
> Cc: stable at vger.kernel.org
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Lyude <cpaul at redhat.com>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 7 ++-
> drivers/gpu/drm/i915/i915_drv.h | 3 ++
> drivers/gpu/drm/i915/intel_drv.h | 2 +
> drivers/gpu/drm/i915/intel_hotplug.c | 76 ++++++++++++++++++++++++++-------
> drivers/gpu/drm/i915/intel_runtime_pm.c | 3 ++
> 5 files changed, 75 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 3eb47fb..5381d9e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1612,6 +1612,9 @@ static int intel_runtime_suspend(struct device *device)
>
> assert_forcewakes_inactive(dev_priv);
>
> + if (!IS_VALLEYVIEW(dev_priv) || !IS_CHERRYVIEW(dev_priv))
> + intel_hpd_poll_enable(dev_priv, true);
> +
> DRM_DEBUG_KMS("Device suspended\n");
> return 0;
> }
> @@ -1667,8 +1670,10 @@ static int intel_runtime_resume(struct device *device)
> * power well, so hpd is reinitialized from there. For
> * everyone else do it here.
> */
> - if (!IS_VALLEYVIEW(dev_priv) && !IS_CHERRYVIEW(dev_priv))
> + if (!IS_VALLEYVIEW(dev_priv) && !IS_CHERRYVIEW(dev_priv)) {
> intel_hpd_init(dev_priv);
> + intel_hpd_poll_enable(dev_priv, false);
> + }
>
> intel_enable_gt_powersave(dev_priv);
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 239a3ec..944c0d0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -283,6 +283,9 @@ struct i915_hotplug {
> u32 short_port_mask;
> struct work_struct dig_port_work;
>
> + struct work_struct poll_enable_work;
> + bool poll_enabled;
> +
> /*
> * if we get a HPD irq from DP and a HPD irq from non-DP
> * the non-DP HPD could block the workqueue on a mode config
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index dcbfdde..cedac13 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1385,6 +1385,8 @@ int intel_dsi_dcs_init_backlight_funcs(struct intel_connector *intel_connector);
>
> /* intel_dvo.c */
> void intel_dvo_init(struct drm_device *dev);
> +/* intel_hotplug.c */
> +void intel_hpd_poll_enable(struct drm_i915_private *dev_priv, bool enabled);
>
>
> /* legacy fbdev emulation in intel_fbdev.c */
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index ec3285f..f23330d 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -455,28 +455,14 @@ void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
> */
> void intel_hpd_init(struct drm_i915_private *dev_priv)
> {
> - struct drm_device *dev = dev_priv->dev;
> - struct drm_mode_config *mode_config = &dev->mode_config;
> - struct drm_connector *connector;
> int i;
>
> for_each_hpd_pin(i) {
> dev_priv->hotplug.stats[i].count = 0;
> dev_priv->hotplug.stats[i].state = HPD_ENABLED;
> }
> - list_for_each_entry(connector, &mode_config->connector_list, head) {
> - struct intel_connector *intel_connector = to_intel_connector(connector);
> - connector->polled = intel_connector->polled;
>
> - /* MST has a dynamic intel_connector->encoder and it's reprobing
> - * is all handled by the MST helpers. */
> - if (intel_connector->mst_port)
> - continue;
> -
> - if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
> - intel_connector->encoder->hpd_pin > HPD_NONE)
> - connector->polled = DRM_CONNECTOR_POLL_HPD;
> - }
> + intel_hpd_poll_enable(dev_priv, false);
>
> /*
> * Interrupt setup is already guaranteed to be single-threaded, this is
> @@ -488,10 +474,69 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
> spin_unlock_irq(&dev_priv->irq_lock);
> }
>
> +void i915_hpd_poll_init_work(struct work_struct *work) {
> + struct drm_i915_private *dev_priv =
> + container_of(work, struct drm_i915_private,
> + hotplug.poll_enable_work);
> + struct drm_device *dev = dev_priv->dev;
> + struct intel_connector *intel_connector;
> + bool enabled;
> +
> + mutex_lock(&dev->mode_config.mutex);
> +
> + enabled = READ_ONCE(dev_priv->hotplug.poll_enabled);
> +
> + for_each_intel_connector(dev, intel_connector) {
> + struct drm_connector *connector = &intel_connector->base;
> +
> + if (enabled) {
> + connector->polled = DRM_CONNECTOR_POLL_CONNECT |
> + DRM_CONNECTOR_POLL_DISCONNECT;
> + } else {
> + connector->polled = intel_connector->polled;
> +
> + /* MST has a dynamic intel_connector->encoder and it's
> + * reprobing is all handled by the MST helpers. */
> + if (intel_connector->mst_port)
> + continue;
I think we need to move the mst check out to the top. MST connectors
should never be polled. The other check which you've lost entirely here
from hpd_init is the initial assignment of polle =
intel_connector->polled. We need that for connectors which don't support
hpd (theres a few on older platforms).
Finally the poll or not should only be done for connectors where we might
pull, i.e. the ones below. Please move the if (enabled) check just inside
that condition.
Essentially: Move the exact loop from hpd_init to here, but change the
last assignement to
connector->polled = enabled ? DRM_CONNECTOR_POLL_CONNECT |
DRM_CONNECTOR_POLL_DISCONNECT : DRM_CONNECTOR_POLL_HPD;
Otherwise I think this looks good now.
-Daniel
> +
> + if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
> + intel_connector->encoder->hpd_pin > HPD_NONE)
> + connector->polled = DRM_CONNECTOR_POLL_HPD;
> + }
> + }
> +
> + if (enabled)
> + drm_kms_helper_poll_enable_locked(dev);
> +
> + mutex_unlock(&dev->mode_config.mutex);
> +
> + /*
> + * We might have missed any hotplugs that happened while we were
> + * in the middle of disabling polling
> + */
> + if (!enabled)
> + drm_helper_hpd_irq_event(dev);
> +}
> +
> +void intel_hpd_poll_enable(struct drm_i915_private *dev_priv, bool enabled)
> +{
> + WRITE_ONCE(dev_priv->hotplug.poll_enabled, enabled);
> +
> + /*
> + * We might already be holding dev->mode_config.mutex, so do this in a
> + * seperate worker
> + * As well, there's no issue if we race here since we always reschedule
> + * this worker anyway
> + */
> + schedule_work(&dev_priv->hotplug.poll_enable_work);
> +}
> +
> void intel_hpd_init_work(struct drm_i915_private *dev_priv)
> {
> INIT_WORK(&dev_priv->hotplug.hotplug_work, i915_hotplug_work_func);
> INIT_WORK(&dev_priv->hotplug.dig_port_work, i915_digport_work_func);
> + INIT_WORK(&dev_priv->hotplug.poll_enable_work, i915_hpd_poll_init_work);
> INIT_DELAYED_WORK(&dev_priv->hotplug.reenable_work,
> intel_hpd_irq_storm_reenable_work);
> }
> @@ -508,6 +553,7 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
>
> cancel_work_sync(&dev_priv->hotplug.dig_port_work);
> cancel_work_sync(&dev_priv->hotplug.hotplug_work);
> + cancel_work_sync(&dev_priv->hotplug.poll_enable_work);
> cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
> }
>
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index f88ef76..b0e9395 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -1099,6 +1099,7 @@ static void vlv_display_power_well_init(struct drm_i915_private *dev_priv)
> if (dev_priv->power_domains.initializing)
> return;
>
> + intel_hpd_poll_enable(dev_priv, false);
> intel_hpd_init(dev_priv);
>
> /* Re-enable the ADPA, if we have one */
> @@ -1120,6 +1121,8 @@ static void vlv_display_power_well_deinit(struct drm_i915_private *dev_priv)
> synchronize_irq(dev_priv->dev->irq);
>
> vlv_power_sequencer_reset(dev_priv);
> +
> + intel_hpd_poll_enable(dev_priv, true);
> }
>
> static void vlv_display_power_well_enable(struct drm_i915_private *dev_priv,
> --
> 2.5.5
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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