On Mon, 30 Nov 2015 15:11:16 +0100,
Daniel Vetter wrote:
> 
> On Mon, Nov 30, 2015 at 02:37:46PM +0100, Takashi Iwai wrote:
> > Implement a new i915_audio_component_ops, get_eld().  It's called by
> > the audio driver to fetch the current ELD of the given HDMI/DP port.
> > It returns the size of ELD bytes if it's valid, or zero if the audio
> > is disabled or unplugged, or a negative error code.
> > 
> > For achieving this, a new field audio_enabled is added to struct
> > intel_digital_port.  This is set/reset at each audio enable/disable
> > call in intel_audio.c.
> > 
> > Signed-off-by: Takashi Iwai <ti...@suse.de>
> > ---
> >  drivers/gpu/drm/i915/intel_audio.c | 40 
> > ++++++++++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_drv.h   |  1 +
> >  include/drm/i915_component.h       |  3 +++
> >  3 files changed, 44 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_audio.c 
> > b/drivers/gpu/drm/i915/intel_audio.c
> > index 0c38cc6c82ae..6b318a8d5dc9 100644
> > --- a/drivers/gpu/drm/i915/intel_audio.c
> > +++ b/drivers/gpu/drm/i915/intel_audio.c
> > @@ -521,6 +521,7 @@ void intel_audio_codec_enable(struct intel_encoder 
> > *intel_encoder)
> >  
> >     connector->eld[6] = drm_av_sync_delay(connector, adjusted_mode) / 2;
> >  
> > +   intel_dig_port->audio_enabled = true;
> >     if (dev_priv->display.audio_codec_enable)
> >             dev_priv->display.audio_codec_enable(connector, intel_encoder,
> >                                                  adjusted_mode);
> > @@ -545,6 +546,7 @@ void intel_audio_codec_disable(struct intel_encoder 
> > *intel_encoder)
> >     struct intel_digital_port *intel_dig_port = enc_to_dig_port(encoder);
> >     enum port port = intel_dig_port->port;
> >  
> > +   intel_dig_port->audio_enabled = false;
> >     if (dev_priv->display.audio_codec_disable)
> >             dev_priv->display.audio_codec_disable(intel_encoder);
> >  
> > @@ -702,6 +704,43 @@ static int i915_audio_component_sync_audio_rate(struct 
> > device *dev,
> >     return 0;
> >  }
> >  
> > +static int i915_audio_component_get_eld(struct device *dev, int port,
> > +                                   bool *enabled,
> > +                                   unsigned char *buf, int max_bytes)
> > +{
> > +   struct drm_i915_private *dev_priv = dev_to_i915(dev);
> > +   struct drm_device *drm_dev = dev_priv->dev;
> > +   struct intel_encoder *intel_encoder;
> > +   struct intel_digital_port *intel_dig_port;
> > +   struct drm_connector *connector;
> > +   unsigned char *eld;
> > +   int ret = -EINVAL;
> > +
> 
> Locking is a bit in-flux atm with atomic, but needs
> dev_priv->dev->mode_config->mutex here to protect against the eld
> changing.

Noted, I'll add it in the next respin.

> > +   mutex_lock(&dev_priv->av_mutex);
> > +   for_each_intel_encoder(drm_dev, intel_encoder) {
> > +           if (intel_encoder->type != INTEL_OUTPUT_DISPLAYPORT &&
> > +               intel_encoder->type != INTEL_OUTPUT_HDMI)
> 
> MST? Not that I have a clue how that should work ;-)

Well, I supposed that MST entry doesn't actually serve for the digital
port, but I'm not entirely sure.  In anyway, the whole MST audio
support shall be added / handled by other Intel people soon later, so
let's keep this as is -- which is the same condition as the current
i915 code.

> > +                   continue;
> > +           intel_dig_port = enc_to_dig_port(&intel_encoder->base);
> > +           if (port == intel_dig_port->port) {
> > +                   ret = 0;
> > +                   *enabled = intel_dig_port->audio_enabled;
> > +                   if (!*enabled)
> > +                           break;
> > +                   connector = drm_select_eld(&intel_encoder->base);
> > +                   if (!connector)
> > +                           break;
> > +                   eld = connector->eld;
> > +                   ret = min(max_bytes, drm_eld_size(eld));
> 
> How can the caller figure out what the eld size is if you use min here? At
> least in drm we just return the size we want if it's too small.

A good point.  The function should return the size "to be written
all", indeed.

> > +                   memcpy(buf, eld, ret);
> > +                   break;
> > +           }
> > +   }
> > +
> > +   mutex_unlock(&dev_priv->av_mutex);
> > +   return ret;
> > +}
> > +
> >  static const struct i915_audio_component_ops i915_audio_component_ops = {
> >     .owner          = THIS_MODULE,
> >     .get_power      = i915_audio_component_get_power,
> > @@ -709,6 +748,7 @@ static const struct i915_audio_component_ops 
> > i915_audio_component_ops = {
> >     .codec_wake_override = i915_audio_component_codec_wake_override,
> >     .get_cdclk_freq = i915_audio_component_get_cdclk_freq,
> >     .sync_audio_rate = i915_audio_component_sync_audio_rate,
> > +   .get_eld        = i915_audio_component_get_eld,
> >  };
> >  
> >  static int i915_audio_component_bind(struct device *i915_dev,
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index 0598932ce623..4afc7560be04 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -798,6 +798,7 @@ struct intel_digital_port {
> >     u32 saved_port_bits;
> >     struct intel_dp dp;
> >     struct intel_hdmi hdmi;
> > +   bool audio_enabled;
> 
> Needs a comment that this is protected by dev_priv->av_mutex.

OK.

> >     enum irqreturn (*hpd_pulse)(struct intel_digital_port *, bool);
> >     bool release_cl2_override;
> >  };
> > diff --git a/include/drm/i915_component.h b/include/drm/i915_component.h
> > index 30d89e0da2c6..058d39e8d57f 100644
> > --- a/include/drm/i915_component.h
> > +++ b/include/drm/i915_component.h
> > @@ -38,6 +38,7 @@
> >   * @codec_wake_override: Enable/Disable generating the codec wake signal
> >   * @get_cdclk_freq: get the Core Display Clock in KHz
> >   * @sync_audio_rate: set n/cts based on the sample rate
> > + * @get_eld: fill the audio state and ELD bytes for the given port
> 
> In 4.4 kerneldoc supports extended in-line comments for struct members
> like this:
> 
> >   */
> >  struct i915_audio_component_ops {
> >     struct module *owner;
> > @@ -46,6 +47,8 @@ struct i915_audio_component_ops {
> >     void (*codec_wake_override)(struct device *, bool enable);
> >     int (*get_cdclk_freq)(struct device *);
> >     int (*sync_audio_rate)(struct device *, int port, int rate);
> 
>       /**
>        * @get_eld:
>        *
>        * lots of blabla, possibly in multiple paragraphs.
>        */
> 
> Please use that layout and put a copy of the more detailed description you
> put into the commit message of how ->get_eld exactly works.
> 
> I did ask for this to get done as part of some of the previous, and it was
> partially done but not exactly how kerneldoc wants it :( But I think we
> need to start somewhere ...

Yeah, it looks like that I missed the back-merge of 4.4-rc although I
thought I did.  Will rebase and rewrite that.


thanks,

Takashi
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