[alsa-devel] HDMI hotplug on Skylake when power well is off

[Takashi Iwai]

On Thu, 16 Jul 2015 11:34:02 +0200,
David Henningsson wrote:
> 
> 
> 
> On 2015-07-16 10:39, Vinod Koul wrote:
> > On Wed, Jul 15, 2015 at 12:59:02PM +0200, Takashi Iwai wrote:
> >> On Wed, 15 Jul 2015 11:05:22 +0200,
> >> David Henningsson wrote:
> >>>
> >>> Hi,
> >>>
> >>> I'm trying to debug an issue here where the HDMI hotplug events are not
> >>> delivered to the audio side when the power well is off. This is on a
> >>> Skylake machine (running in HDA mode).
> >>>
> >>> I'm not sure whether the problem is upstream or due to my own patches
> >>> while testing, so I was wondering how this is supposed to be working, so
> >>> I can troubleshoot further?
> >>>
> >>> Should there be an IRQ on the HDA controller even if the power well is
> >>> off, and if not, how should the audio driver be notified that an HDMI
> >>> hotplug event has happened?
> >>
> >> I thought this has been always a problem when the runtime PM is
> >> enabled, no matter whether the power well state is.
> > Shouldn't the hotplug action turn on the power well? Then notification for
> > audio side should get propagated as power well is On
> 
> While the video side can turn the power well on, maybe there are other 
> things that needs to be turned on from the audio driver?

Yes.  This was supposed to work with WAKEEN bits, but this didn't work
as expected, after all.

> >> IMO, a cleaner solution would be rather the notifier implementation in
> >> software, e.g. extend the i915 component to pass the audio side ops
> >> for notification.
> > Yes that should be added but I would prefer we have hw do that as well
> 
> So I took a quick stab at this and tried to write down a draft, but I 
> got stuck trying to figure out how to wake up the audio codecs from the 
> hdac_i915.c file. I'm not sure how to do this with the recent reorg as I 
> don't want to break the ASoC version of the driver by including the 
> wrong header files.
> 
> See attached patch (which is a very rough draft, not even compile 
> tested), maybe you or Takashi could offer some insight w r t whether I'm 
> on the right track, and how to proceed?

Well, at this time, it's not that easy, unfortunately.  We need to
propagate the notification to a specific codec, not to (only) a bus.
And there will be multiple outputs.  So it'll be an array or list.

Also, ELD and some other bits can be stored there to share between
audio and gfx, too.  This is a big bonus as it allows us to avoid the
read via the often unstable hardware access.

An unclear thing so far is the mapping between the audio codec and the
gfx output.  And this is also the missing piece as of now.  User can't
know which audio output corresponds to which gfx output.  So this is
the first question: is there any good way to know this mapping?

If the mapping is static and can be known at the probe time, we can
register the notifier and assign ELD record and gfx mapping for each
HDMI/DP codec.


thanks,

Takashi

> 
> -- 
> David Henningsson, Canonical Ltd.
> https://launchpad.net/~diwic
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 8ae6f7f..0eaac41 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -45,6 +45,7 @@
>  #include <drm/intel-gtt.h>
>  #include <drm/drm_legacy.h> /* for struct drm_dma_handle */
>  #include <drm/drm_gem.h>
> +#include <drm/i915_component.h>
>  #include <linux/backlight.h>
>  #include <linux/hashtable.h>
>  #include <linux/intel-iommu.h>
> @@ -1752,6 +1753,7 @@ struct drm_i915_private {
>  	struct drm_property *force_audio_property;
>  
>  	/* hda/i915 audio component */
> +	struct i915_audio_component *audio_component;
>  	bool audio_component_registered;
>  
>  	uint32_t hw_context_size;
> diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
> index ef34257..3799d88 100644
> --- a/drivers/gpu/drm/i915/intel_audio.c
> +++ b/drivers/gpu/drm/i915/intel_audio.c
> @@ -424,6 +424,9 @@ void intel_audio_codec_enable(struct intel_encoder *intel_encoder)
>  
>  	if (dev_priv->display.audio_codec_enable)
>  		dev_priv->display.audio_codec_enable(connector, intel_encoder, mode);
> +
> +	if (acomp && acomp->cb_ops && acomp->cb_ops->hotplug_notify)
> +		acomp->cb_ops->hotplug_notify(acomp->hdac_bus, true);
>  }
>  
>  /**
> @@ -437,9 +440,13 @@ void intel_audio_codec_disable(struct intel_encoder *encoder)
>  {
>  	struct drm_device *dev = encoder->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct i915_audio_component *acomp = dev_priv->audio_component;
>  
>  	if (dev_priv->display.audio_codec_disable)
>  		dev_priv->display.audio_codec_disable(encoder);
> +
> +	if (acomp && acomp->cb_ops && acomp->cb_ops->hotplug_notify)
> +		acomp->cb_ops->hotplug_notify(acomp->hdac_bus, false);
>  }
>  
>  /**
> @@ -529,12 +536,14 @@ static int i915_audio_component_bind(struct device *i915_dev,
>  				     struct device *hda_dev, void *data)
>  {
>  	struct i915_audio_component *acomp = data;
> +	struct drm_i915_private *dev_priv = dev_to_i915(i915_dev);
>  
>  	if (WARN_ON(acomp->ops || acomp->dev))
>  		return -EEXIST;
>  
>  	acomp->ops = &i915_audio_component_ops;
>  	acomp->dev = i915_dev;
> +	dev_priv->audio_component = acomp;
>  
>  	return 0;
>  }
> @@ -543,9 +552,11 @@ static void i915_audio_component_unbind(struct device *i915_dev,
>  					struct device *hda_dev, void *data)
>  {
>  	struct i915_audio_component *acomp = data;
> +	struct drm_i915_private *dev_priv = dev_to_i915(i915_dev);
>  
>  	acomp->ops = NULL;
>  	acomp->dev = NULL;
> +	dev_priv->audio_component = NULL;
>  }
>  
>  static const struct component_ops i915_audio_component_bind_ops = {
> diff --git a/include/drm/i915_component.h b/include/drm/i915_component.h
> index c9a8b64..3feab48 100644
> --- a/include/drm/i915_component.h
> +++ b/include/drm/i915_component.h
> @@ -24,8 +24,11 @@
>  #ifndef _I915_COMPONENT_H_
>  #define _I915_COMPONENT_H_
>  
> +struct hdac_bus;
> +
>  struct i915_audio_component {
>  	struct device *dev;
> +	struct hdac_bus *hdac_bus;
>  
>  	const struct i915_audio_component_ops {
>  		struct module *owner;
> @@ -34,6 +37,11 @@ struct i915_audio_component {
>  		void (*codec_wake_override)(struct device *, bool enable);
>  		int (*get_cdclk_freq)(struct device *);
>  	} *ops;
> +
> +	const struct i915_audio_component_cb_ops {
> +		struct module *owner;
> +		void (*hotplug_notify)(struct hdac_bus *, bool enable);
> +	} *cb_ops;
>  };
>  
>  #endif /* _I915_COMPONENT_H_ */
> diff --git a/sound/hda/hdac_i915.c b/sound/hda/hdac_i915.c
> index 442500e..0ec49a6 100644
> --- a/sound/hda/hdac_i915.c
> +++ b/sound/hda/hdac_i915.c
> @@ -115,6 +115,8 @@ static void hdac_component_master_unbind(struct device *dev)
>  {
>  	struct i915_audio_component *acomp = hdac_acomp;
>  
> +	acomp->cb_ops = NULL;
> +	acomp->hdac_bus = NULL;
>  	module_put(acomp->ops->owner);
>  	component_unbind_all(dev, acomp);
>  	WARN_ON(acomp->ops || acomp->dev);
> @@ -125,6 +127,31 @@ static const struct component_master_ops hdac_component_master_ops = {
>  	.unbind = hdac_component_master_unbind,
>  };
>  
> +static const struct i915_ hdac_component_master_ops = {
> +	.bind = hdac_component_master_bind,
> +	.unbind = hdac_component_master_unbind,
> +};
> +
> +static const struct i915_audio_component_cb_ops i915_audio_component_cb_ops = {
> +	.owner		= THIS_MODULE,
> +	.hotplug_notify	= i915_audio_component_hotplug_notify,
> +};
> +
> +
> +static void i915_audio_component_hotplug_notify(struct hdac_bus *bus, bool enable)
> +{
> +	struct hda_codec *codec;
> +
> +	codec_dbg("Received HDMI hotplug callback (enable = %d)", (int) enable);
> +
> +	// TODO: Not sure about this part - with the new reorg, maybe I can't access
> +	// codec->jackpoll_work from this file?
> +	list_for_each_codec(codec, bus)
> +		schedule_delayed_work(&codec->jackpoll_work,
> +			codec->jackpoll_interval);
> +
> +}
> +
>  static int hdac_component_master_match(struct device *dev, void *data)
>  {
>  	/* i915 is the only supported component */
> @@ -160,6 +187,9 @@ int snd_hdac_i915_init(struct hdac_bus *bus)
>  		ret = -ENODEV;
>  		goto out_master_del;
>  	}
> +	acomp->cb_ops = &i915_audio_component_cb_ops;
> +	acomp->hdac_bus = bus;
> +
>  	dev_dbg(dev, "bound to i915 component master\n");
>  
>  	return 0;