Re: [PATCH 5/5] ALSA/i915: Check power well API existense before calling

[Takashi Iwai <tiwai@suse.de>]

At Mon, 13 May 2013 11:55:14 +0000,
Wang, Xingchao wrote:
> 
> Hi David,
> 
> 
> > -----Original Message-----
> > From: alsa-devel-bounces@alsa-project.org
> > [mailto:alsa-devel-bounces@alsa-project.org] On Behalf Of David Henningsson
> > Sent: Monday, May 13, 2013 4:29 PM
> > To: Wang Xingchao
> > Cc: alsa-devel@alsa-project.org; daniel@ffwll.ch; tiwai@suse.de; Lin,
> > Mengdong; intel-gfx@lists.freedesktop.org; Li, Jocelyn; Barnes, Jesse;
> > Girdwood, Liam R; Zanoni, Paulo R
> > Subject: Re: [alsa-devel] [PATCH 5/5] ALSA/i915: Check power well API
> > existense before calling
> > 
> > On 05/13/2013 09:37 AM, Wang Xingchao wrote:
> > > I915 module maybe loaded after snd_hda_intel, the power-well API
> > > doesnot exist in such case. This patch intended to avoid loading
> > > dependency between snd-hda-intel and i915 module.
> > 
> > Hi Xingchao and thanks for working on this.
> > 
> > This patch seems to re-do some of the work done in other patches (a lot of lines
> > removed), so it's a little hard to follow. But I'll try to write some overall
> > comments on how I have envisioned things...
> > 
> > 1. I don't think there's any need to create an additional kernel module, we can
> > just let hda_i915.c be in the snd-hda-intel.ko module, and only compile it if
> > DRM_I915 is defined.
> > 
> > 2. We don't need an IS_HSW macro on the audio side. Instead declare a new
> > AZX_DCAPS_NEED_I915_POWER (or similar) driver quirk.
> > 
> > 3. Somewhere in the beginning of the probing in hda_intel.c, we'll need
> > something like:
> > 
> > if (driver_caps & AZX_DCAPS_NEED_I915_POWER)
> >    hda_i915_init(chip);
> > 
> > 4. The hda_i915_init does not need to be exported (they're now both in the
> > same module). hda_i915.h could have something like:
> > 
> > #ifdef DRM_I915
> >    void hda_i915_init(chip);
> > #else
> >    #define hda_i915_init(chip) do {} while(0) #endif
> 
> Thanks your suggestions. Will change them in next version.

A question is what to do if a Haswell controller is loaded without
i915 driver.  Shouldn't we warn?


Takashi