[Intel-gfx] [PATCH] drm/i915: delay hotplug scheduling

[Guang Bai]

On Wed, 26 Sep 2018 16:44:16 -0700
Guang Bai <guang.bai at intel.com> wrote:

> On Tue, 25 Sep 2018 10:18:36 +0300
> Jani Nikula <jani.nikula at intel.com> wrote:
> 
> > On some systems we get the hotplug irq on unplug before the DDC pins
> > have been disconnected, resulting in connector status remaining
> > connected. Since previous attempts at using hotplug live status
> > before DDC have failed, the only viable option is to reduce the
> > window for mistakes. Delay the hotplug processing.
> > 
> > Reference:
> > http://mid.mail-archive.com/CAB4CAwcfj32FovZwpTbekvHpoc3gG0sVbNtW8jeXRcp5qwEsmw@mail.gmail.com
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107125
> > Reported-by: Chris Chiu <chiu at endlessm.com> Tested-by: Chris Chiu
> > <chiu at endlessm.com> Cc: Chris Chiu <chiu at endlessm.com>
> > Cc: Guang Bai <guang.bai at intel.com>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h      |  2 +-
> >  drivers/gpu/drm/i915/intel_hotplug.c | 16 +++++++++++-----
> >  2 files changed, 12 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > b/drivers/gpu/drm/i915/i915_drv.h index 8624b4bdc242..4378be7a20d5
> > 100644 --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -286,7 +286,7 @@ enum hpd_pin {
> >  #define HPD_STORM_DEFAULT_THRESHOLD 5
> >  
> >  struct i915_hotplug {
> > -	struct work_struct hotplug_work;
> > +	struct delayed_work hotplug_work;
> >  
> >  	struct {
> >  		unsigned long last_jiffies;
> > diff --git a/drivers/gpu/drm/i915/intel_hotplug.c
> > b/drivers/gpu/drm/i915/intel_hotplug.c index
> > 648a13c6043c..ce9bedbedcd1 100644 ---
> > a/drivers/gpu/drm/i915/intel_hotplug.c +++
> > b/drivers/gpu/drm/i915/intel_hotplug.c @@ -110,6 +110,9 @@ enum
> > hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv, }
> >  }
> >  
> > +/* Delay between irq and hotplug detect processing */
> > +#define HOTPLUG_DELAY_MS		300
> > +
> >  #define HPD_STORM_DETECT_PERIOD		1000
> >  #define HPD_STORM_REENABLE_DELAY	(2 * 60 * 1000)
> >  
> > @@ -319,7 +322,8 @@ static void i915_digport_work_func(struct
> > work_struct *work) spin_lock_irq(&dev_priv->irq_lock);
> >  		dev_priv->hotplug.event_bits |= old_bits;
> >  		spin_unlock_irq(&dev_priv->irq_lock);
> > -		schedule_work(&dev_priv->hotplug.hotplug_work);
> > +
> > schedule_delayed_work(&dev_priv->hotplug.hotplug_work,
> > +
> > msecs_to_jiffies(HOTPLUG_DELAY_MS)); }
> >  }
> >  
> > @@ -329,7 +333,7 @@ static void i915_digport_work_func(struct
> > work_struct *work) static void i915_hotplug_work_func(struct
> > work_struct *work) {
> >  	struct drm_i915_private *dev_priv =
> > -		container_of(work, struct drm_i915_private,
> > hotplug.hotplug_work);
> > +		container_of(work, struct drm_i915_private,
> > hotplug.hotplug_work.work); struct drm_device *dev = &dev_priv->drm;
> >  	struct intel_connector *intel_connector;
> >  	struct intel_encoder *intel_encoder;
> > @@ -466,7 +470,8 @@ void intel_hpd_irq_handler(struct
> > drm_i915_private *dev_priv, if (queue_dig)
> >  		queue_work(dev_priv->hotplug.dp_wq,
> > &dev_priv->hotplug.dig_port_work); if (queue_hp)
> > -		schedule_work(&dev_priv->hotplug.hotplug_work);
> > +
> > schedule_delayed_work(&dev_priv->hotplug.hotplug_work,
> > +
> > msecs_to_jiffies(HOTPLUG_DELAY_MS)); }
> >  
> >  /**
> > @@ -586,7 +591,8 @@ void intel_hpd_poll_init(struct drm_i915_private
> > *dev_priv) 
> >  void intel_hpd_init_work(struct drm_i915_private *dev_priv)
> >  {
> > -	INIT_WORK(&dev_priv->hotplug.hotplug_work,
> > i915_hotplug_work_func);
> > +	INIT_DELAYED_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_init_work,
> > i915_hpd_poll_init_work);
> > INIT_DELAYED_WORK(&dev_priv->hotplug.reenable_work, @@ -604,7
> > +610,7 @@ void intel_hpd_cancel_work(struct drm_i915_private
> > *dev_priv) spin_unlock_irq(&dev_priv->irq_lock);
> > cancel_work_sync(&dev_priv->hotplug.dig_port_work);
> > -	cancel_work_sync(&dev_priv->hotplug.hotplug_work);
> > +	cancel_delayed_work_sync(&dev_priv->hotplug.hotplug_work);
> >  	cancel_work_sync(&dev_priv->hotplug.poll_init_work);
> >  	cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
> >  }  
> Jani - With these changes, my customer platform still fails the
> HDMI hot-plug test - slowly unplug the HDMI cable,
> the /sys/class/drm/card0/card0-HDMI-A-1/status still shows connected
> state. My previous experiments indicated adding bigger delay before
> calling "drm_kms_helper_hotplug_event(dev)", which lead to reading the
> EDID, didn't have solid passing test results. The POC changes with
> passing results from onsite utilize following algorithm - 
> 1. in the hot-plug worker function, check the PCH hot-plug status pin
> to see it's disconnected or not in a 3 x 100ms loop
> 2. if "disconnected" is confirmed after this loop, honor it and do not
> read the EDID
> 3. if "connected" is confirmed after this loop, honor it after EDID
> read is successful
> The overhead for this algorithm is to access the HPD status from all
> platform PCHs and some hot-plug code refactoring would be needed.
> (sorry for the late reply as of customer platform preparations, etc)
> 
Double checked my archives - the EDID reading is actually done in the
"intel_encoder->hotplug()" via "drm_helper_probe_detect()"
sorry for the typo.
-Guang
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