Message-ID: <20080709172637.GA5355@vespa.holoscopio.com>
Date:	Wed, 9 Jul 2008 14:26:38 -0300
From:	Thadeu Lima de Souza Cascardo <cascardo@...aslivre.org>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Wait for all codecs to be ready if doing a cold reset

On Wed, Jul 09, 2008 at 08:23:12PM +0200, Takashi Iwai wrote:
> At Tue, 8 Jul 2008 14:31:22 -0300,
> Thadeu Lima de Souza Cascardo wrote:
> > 
> > On Wed, Jul 09, 2008 at 05:07:17PM +0200, Takashi Iwai wrote:
> > > At Tue, 8 Jul 2008 13:59:32 -0300,
> > > Thadeu Lima de Souza Cascardo wrote:
> > > > 
> > > > On Tue, Jul 08, 2008 at 12:16:35PM +0200, Takashi Iwai wrote:
> > > > > At Mon, 7 Jul 2008 14:36:55 -0300,
> > > > > Thadeu Lima de Souza Cascardo wrote:
> > > > > > 
> > > > > > On Mon, Jul 07, 2008 at 06:39:09PM +0200, Takashi Iwai wrote:
> > > > > > > At Sun, 6 Jul 2008 14:15:56 -0300,
> > > > > > > Thadeu Lima de Souza Cascardo wrote:
> > > > > > > > 
> > > > > > > > If AC97_POWER_SAVE is enabled, intel8x0 does a cold reset when
> > > > > > > > initializing the codecs. While resuming, it does not wait for all codecs
> > > > > > > > to be active. Sound card does not work after a resume without it,
> > > > > > > > however. This patch fixes it.
> > > > > > > 
> > > > > > > Thanks for the patch.
> > > > > > > 
> > > > > > > But, I still don't figure out why this is needed.
> > > > > > > In the else block (with the comment "resume phase"), you can find the
> > > > > > > loop to wait for the all *probed* codecs.  The difference with the
> > > > > > > code you moved is that it checks only the bits corresponding to the
> > > > > > > already probed codecs.  In other words, the other bits should be
> > > > > > > irrelevant with the hardware.
> > > > > > > 
> > > > > > > I guess it's not about the loop but the additional 1/4 sec delay that
> > > > > > > did fix the resume on your device.  Please check how is the status
> > > > > > > bits and whether it passed the loop in the middle.
> > > > > > > 
> > > > > > > 
> > > > > > > Takashi
> > > > > > > 
> > > > > > > 
> > > > > > 
> > > > > > The 1/4 sec delay came in my mind as one of the possible reasons, and
> > > > > > that's why I've made some tests. status and nstatus are 0x200, while
> > > > > > codec_isr_bits is 0x300. The loop waits for the status register give us
> > > > > > 0x300 as the active codecs, instead of the only one probed. Since the
> > > > > > cold reset in the case of a power saving cleans up all codec registers,
> > > > > > it is needed that we wait for all codecs again (like in the probe case).
> > > > > 
> > > > > You loaded the modem driver as well?
> > > > > If so, what happens if you unload modem driver?
> > > > > 
> > > > > 
> > > > > thanks,
> > > > > 
> > > > > Takashi
> > > > > 
> > > > 
> > > > The modem driver has always been loaded. Unloading it with my patch
> > > > works OK.
> > > 
> > > Well, I meant to unload the modem driver *without* your patch.
> > > That is, does it the unmodified version work if you unload the modem
> > > driver beforehand (e.g. adding it to blacklist)?
> > > 
> > > 
> > > thanks,
> > > 
> > > Takashi
> > > 
> > 
> > I blacklisted snd_intel8x0m, rebooted, it was not loaded, sound worked.
> > Suspended, resumed, sound didn't work, as usual.
> 
> Thanks for checking.
> 
> I still don't understand why you need to wait for all codecs.
> Certainly the secondary one is the modem codec, and it has nothing to
> do with the audio codec...
> 
> I don't mind to apply the patch as is since it's harmless except for
> the extra delay.  But, the real question is whether it's the codec
> probe or just another delay.
> 
> Note that not all devices have codecs filling all slots like yours.
> On the later ICH, it has three slots while usually two of them are
> used.  So, on these hardwares, your code results always in just a 25ms
> delay.
> 
> Anyway, could you give your sign-off?
> 
> 
> thanks,
> 
> Takashi


Maybe we could treat this as a quirk in my device, which is 8086:2485?

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...aslivre.org>

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