Hi Jaroslav, > -----Original Message----- > From: alsa-devel-boun...@alsa-project.org > [mailto:alsa-devel-boun...@alsa-project.org] On Behalf Of Jaroslav Kysela > Sent: Monday, May 13, 2013 4:56 PM > To: David Henningsson > Cc: alsa-de...@alsa-project.org; Girdwood, Liam R; ti...@suse.de; Lin, > Mengdong; intel-gfx@lists.freedesktop.org; Wang Xingchao; Li, Jocelyn; > Barnes, Jesse; dan...@ffwll.ch; Zanoni, Paulo R > Subject: Re: [alsa-devel] [PATCH 5/5] ALSA/i915: Check power well API > existense before calling > > 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?
I think the dependency here is not real. In case the i915 loaded first, the callback doesnot exist and do nothing, it's safe. In case snd-hda-intel loaded first, and need pause there to wait i915 module loading, this callback is helpful to notify snd-hda-intel the proper time to check symbol again. Thanks --xingchao _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
