Re: [PATCH 1/3] drm/i915/hda: Add audio component stub

Imre Deak
2016-04-07T12:30:49Z

On to, 2016-04-07 at 14:55 +0300, Ville Syrjälä wrote:
> On Thu, Apr 07, 2016 at 12:57:22PM +0200, Takashi Iwai wrote:
> > From: Imre Deak <imre.deak@intel.com>
> >
> > User may pass nomodeset or i915.modeset=0 option to disable i915
> > KMS
> > explicitly.  Although this itself works fine, it breaks the weak
> > dependency the HD-audio driver requires, and it's the reason the
> > delayed component binding isn't implemented in HD-audio.  Since
> > i915
> > doesn't notify its disablement, HD-audio would be blocked
> > unnecessarily endlessly, waiting for the bind with i915.
> >
> > This patch introduces a stub audio component binding when i915
> > driver
> > is loaded with KMS off like the boot options above.  Then i915
> > driver
> > still registers the slave component but with the new "disabled" ops
> > flag, so that the master component (HD-audio) can know clearly the
> > slave state.
> >
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c    | 34 +++++++++++++--------
> >  drivers/gpu/drm/i915/intel_audio.c | 61
> > ++++++++++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_drv.h   |  2 ++
> >  include/drm/i915_component.h       |  5 ++++
> >  4 files changed, 90 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c
> > b/drivers/gpu/drm/i915/i915_drv.c
> > index 20e82008b8b6..21c6bac5468e 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -950,6 +950,19 @@ static int i915_pci_probe(struct pci_dev
> > *pdev, const struct pci_device_id *ent)
> >   struct intel_device_info *intel_info =
> >   (struct intel_device_info *) ent->driver_data;
> >
> > + if (!(driver.driver_features & DRIVER_MODESET)) {
> > + /*
> > +  * Notify the HDA driver so that it doesn't block
> > waiting for
> > +  * i915 to become ready.
> > +  */
> > + i915_audio_component_stub_init(&pdev->dev);
> > +
> > + /* Silently fail loading to not upset userspace.
> > */
> > + DRM_DEBUG_DRIVER("KMS and UMS disabled.\n");
> > +
> > + return 0;
> > + }
> > +
>
> Moving this here means we're actually going to bind to the device
> even
> w/o DRIVER_MODESET. Hopefully the fact that we don't register with
> any
> subsystems would make that OK. But since we need the actual device
> for
> the component stuff, I guess this is the only way.

Yes, the need for the device was the reason I moved this here. An
alternative would be to add a miscdevice. I wanted to keep things
simple and didn't see any problem of keeping the device bound, so chose
this way.

One other thing I was thinking about is to also bind the stub component
if the real probing failed to make things more consistent and avoid the
longish timeout on the HDA side. This would also get messier with the
miscdevice approach, since the probe error is not propagated to the
caller of pci_register_driver(). If people don't see a problem with
this I could add this in the next version.

> >   if (IS_PRELIMINARY_HW(intel_info) &&
> > !i915.preliminary_hw_support) {
> >   DRM_INFO("This hardware requires preliminary
> > hardware support.\n"
> >    "See
> > CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT, and/or modparam
> > preliminary_hw_support\n");
> > @@ -979,8 +992,14 @@ static int i915_pci_probe(struct pci_dev
> > *pdev, const struct pci_device_id *ent)
> >  static void
> >  i915_pci_remove(struct pci_dev *pdev)
> >  {
> > - struct drm_device *dev = pci_get_drvdata(pdev);
> > + struct drm_device *dev;
> >
> > + if (!(driver.driver_features & DRIVER_MODESET)) {
> > + i915_audio_component_stub_cleanup(&pdev->dev);
> > + return;
> > + }
> > +
> > + dev = pci_get_drvdata(pdev);
> >   drm_put_dev(dev);
> >  }
> >
> > @@ -1747,24 +1766,15 @@ static int __init i915_init(void)
> >   driver.driver_features &= ~DRIVER_MODESET;
> >  #endif
> >
> > - if (!(driver.driver_features & DRIVER_MODESET)) {
> > - /* Silently fail loading to not upset userspace.
> > */
> > - DRM_DEBUG_DRIVER("KMS and UMS disabled.\n");
> > - return 0;
> > - }
> > -
> >   if (i915.nuclear_pageflip)
> >   driver.driver_features |= DRIVER_ATOMIC;
> >
> > - return drm_pci_init(&driver, &i915_pci_driver);
> > + return pci_register_driver(&i915_pci_driver);
> >  }
> >
> >  static void __exit i915_exit(void)
> >  {
> > - if (!(driver.driver_features & DRIVER_MODESET))
> > - return; /* Never loaded a driver. */
> > -
> > - drm_pci_exit(&driver, &i915_pci_driver);
> > + pci_unregister_driver(&i915_pci_driver);
> >  }
> >
> >  module_init(i915_init);
> > diff --git a/drivers/gpu/drm/i915/intel_audio.c
> > b/drivers/gpu/drm/i915/intel_audio.c
> > index 30f921421b0c..bd9e9760903a 100644
> > --- a/drivers/gpu/drm/i915/intel_audio.c
> > +++ b/drivers/gpu/drm/i915/intel_audio.c
> > @@ -835,3 +835,64 @@ void i915_audio_component_cleanup(struct
> > drm_i915_private *dev_priv)
> >   component_del(dev_priv->dev->dev,
> > &i915_audio_component_bind_ops);
> >   dev_priv->audio_component_registered = false;
> >  }
> > +
> > +static const struct i915_audio_component_ops
> > i915_audio_component_stub_ops = {
> > + .owner = THIS_MODULE,
> > + .disabled = true,
> > +};
> > +
> > +static int i915_audio_component_stub_bind(struct device
> > *i915_stub_dev,
> > +   struct device *hda_dev,
> > void *data)
> > +{
> > + struct i915_audio_component *acomp = data;
> > +
> > + if (WARN_ON(acomp->ops || acomp->dev))
> > + return -EEXIST;
> > +
> > + acomp->ops = &i915_audio_component_stub_ops;
> > + acomp->dev = i915_stub_dev;
> > +
> > + return 0;
> > +}
> > +
> > +static void i915_audio_component_stub_unbind(struct device
> > *i915_stub_dev,
> > +      struct device
> > *hda_dev, void *data)
> > +{
> > + struct i915_audio_component *acomp = data;
> > +
> > + acomp->ops = NULL;
> > + acomp->dev = NULL;
> > +}
> > +
> > +static const struct component_ops
> > i915_audio_component_stub_bind_ops = {
> > + .bind = i915_audio_component_stub_bind,
> > + .unbind = i915_audio_component_stub_unbind,
> > +};
> > +
> > +static const struct file_operations component_stub_dev_ops = {
> > + .owner = THIS_MODULE,
> > +};
> > +
> > +static bool i915_audio_component_stub_registered;
> > +
> > +void i915_audio_component_stub_init(struct device *dev)
> > +{
> > + int ret;
> > +
> > + ret = component_add(dev,
> > &i915_audio_component_stub_bind_ops);
> > + if (ret < 0) {
> > + DRM_ERROR("failed to add audio stub component
> > (%d)\n", ret);
> > + return;
> > + }
> > +
> > + i915_audio_component_stub_registered = true;
>
> Maybe just fail the probe on error and avoid the flag?

Makes sense, will change that.

> > +}
> > +
> > +void i915_audio_component_stub_cleanup(struct device *dev)
> > +{
> > + if (!i915_audio_component_stub_registered)
> > + return;
> > +
> > + component_del(dev, &i915_audio_component_stub_bind_ops);
> > + i915_audio_component_stub_registered = false;
> > +}
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index 4c027d69fac9..e1d9c33b113e 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1056,6 +1056,8 @@ void intel_audio_codec_enable(struct
> > intel_encoder *encoder);
> >  void intel_audio_codec_disable(struct intel_encoder *encoder);
> >  void i915_audio_component_init(struct drm_i915_private *dev_priv);
> >  void i915_audio_component_cleanup(struct drm_i915_private
> > *dev_priv);
> > +void i915_audio_component_stub_init(struct device *dev);
> > +void i915_audio_component_stub_cleanup(struct device *dev);
> >
> >  /* intel_display.c */
> >  extern const struct drm_plane_funcs intel_plane_funcs;
> > diff --git a/include/drm/i915_component.h
> > b/include/drm/i915_component.h
> > index b46fa0ef3005..33da85aa70c3 100644
> > --- a/include/drm/i915_component.h
> > +++ b/include/drm/i915_component.h
> > @@ -39,6 +39,11 @@ struct i915_audio_component_ops {
> >    */
> >   struct module *owner;
> >   /**
> > +  * @disabled: i915 driver loaded with modeset=0, the
> > services provided
> > +  * via the audio component interface are not available.
> > +  */
> > + bool disabled;
> > + /**
> >    * @get_power: get the POWER_DOMAIN_AUDIO power well
> >    *
> >    * Request the power well to be turned on.
> > --
> > 2.8.1
> >
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