Date 13.5.2013 10:28, David Henningsson wrote:
> 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
>
> 5. You're saying this patch is about avoid loading dependency between
> snd-hda-intel and i915 module. That does not make sense to me, since the
> powerwell API is in the i915 module, snd-hda-intel must load it when it
> wants to enable power on haswell, right? Thus there is a loading
> dependency. If the i915 module is not loaded at that point, we must wait
> for it to load, so we can have proper power, instead of continuing
> probing without the power well?
Looking to the code, if the drm code requires a callback to the audio
code, I would just register it in the audio driver init phase and
unregister it when snd-hda-intel is unloaded. This cross module loading
dependency looks really bad. Or it is not allowed to load the audio
driver later than DRM one?
Jaroslav
--
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project; Red Hat, Inc.
