linux-kernel - Re: next-20151208 - CONFIG_SND_HDA

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Message-ID: <s5hzixkyvn9.wl-tiwai@suse.de>
Date:	Wed, 09 Dec 2015 07:38:02 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Valdis Kletnieks <Valdis.Kletnieks@...edu>
Cc:	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: next-20151208 - CONFIG_SND_HDA_I915

On Wed, 09 Dec 2015 04:46:38 +0100,
Valdis Kletnieks wrote:
> 
> I'm experiencing a spot of trouble with this commit:
> 
> commit aad730d0704545ad97654bd929b0aba05adb1436
> Author: Takashi Iwai <tiwai@...e.de>
> Date:   Mon Dec 2 13:33:57 2013 +0100
> 
>     ALSA: hda - Always do delayed probes for HD-audio devices
> 
> That adds some code:
> 
> #ifndef CONFIG_SND_HDA_I915
> 	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
> 		dev_err(card->dev, "Haswell must build in CONFIG_SND_HDA_I915\n");
> 
> "Oh, bother" -- Winnie the Pooh
> 
> So I go looking how to fix this, and 'make menuconfig' tells me:
> 
> Symbol: SND_HDA_I915 [=n]                                                                                             x  
>   x Type  : boolean                                                                                                       x  
>   x   Defined at sound/hda/Kconfig:8                                                                                      x  
>   x   Depends on: SOUND [=y] && !M68K && !UML && SND [=y] && DRM_I915 [=n] && SND_HDA_CORE [=y]
> 
> And why is DRM_I915=n?
> 
> # lspci | grep NV
> 01:00.0 VGA compatible controller: NVIDIA Corporation GF108GLM [NVS 5200M] (rev a1)
> 
> Because this Dell laptop has NVidia graphics onboard, and no sign of I915
> graphics that needs I915 DRM.

Right, and this is exactly the purpose of this warning.

> I think the infrastructure that you're trying to re-use from DRM_I915 needs
> to be moved to another symbol which can be SELECT/DEPEND by both DRM_I915
> and SND_HSA_I915.

The HD-audio driver does soft-binding with i915, and the check above
was for the case where i915 is *not* included although the audio
driver tries binding.  This check was mostly for Haswell/Broadwell
HDMI/DP.  Now we see this often on linux-next due to the recent change
to allow i915 binding even on old PCHs.

So, the check itself is correct, per se, but it becomes superfluous in
many cases now.  I already addressed this, but forgot to submit /
merge.  The patches will be seen shortly later on alsa-devel ML.


thanks,

Takashi
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