linux-kernel - Re: [PATCH] ALSA: hda_intel - revert a quirk that breaks all VIA chipsets

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Date:	Tue, 29 Nov 2011 11:30:02 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Marc Vertes <marc.vertes@...fox.com>
Cc:	linux-kernel@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH] ALSA: hda_intel - revert a quirk that breaks all VIA chipsets

At Tue, 29 Nov 2011 11:13:19 +0100,
Marc Vertes wrote:
> 
> 
> This quirk sould be reverted. It has the following probems:
> 
> 1) It breaks the default setup of all VIA chipset models (vendor
> 0x1106, product 0x3288),

Not exactly true.  It's a PCI subsystem ID, not PCI ID.  A sane
machine with a proper PCI SSID won't hit this problem.  Only machines
with lazy BIOS programmers hit since they have no proper PCI SSID but
copy PCI ID.

Though, it doesn't look good to add a broken ID like this, indeed.

> at least a dozen models are concerned, from VIA-VT82xx
> to VIA-VT17xx and VT20xx. All those chips rely on azx_via_get_position()
> to handle correctly dma transfers during capture. Using POS_FIX_LPIB
> instead of POS_FIX_VIACOMBO leads to partially corrupted input buffers
> during capture. The effects of this bug are not immediately visible,
> it took strong DSP expertise, some expensive signal generator and a spectrum
> analyzer to identify it and verify correct behaviour using original default.
> 
> 2) The string "ASUS MV2-MX SE" refers to a motherboard, not a sound chipset
> family, which is misleading on the impact of the quirk.

The quirk was intended really only for this ASUS mobo, not for
chipset.


> 3) It's almost certain that the quirk did not fix the real problem, if there
> was one. Refer to original submission:
> http://mailman.alsa-project.org/pipermail/alsa-devel/2010-February/025109.html

So, I'm for applying it.  But could you rephrase the change log with
the consideration of the above and re-submit?


thanks,

Takashi


> 
> Thanks,
> 
> Marc
> --
> 
> Signed-of-by: Marc Vertes <mvertes@...fox.com>
> 
> --- linux-3.2-rc3/sound/pci/hda/hda_intel.c.orig	2011-11-24 05:20:28.000000000 +0100
> +++ linux-3.2-rc3/sound/pci/hda/hda_intel.c	2011-11-28 17:29:01.044095455 +0100
> @@ -2508,7 +2508,6 @@ static struct snd_pci_quirk position_fix
>  	SND_PCI_QUIRK(0x1043, 0x81b3, "ASUS", POS_FIX_LPIB),
>  	SND_PCI_QUIRK(0x1043, 0x81e7, "ASUS M2V", POS_FIX_LPIB),
>  	SND_PCI_QUIRK(0x104d, 0x9069, "Sony VPCS11V9E", POS_FIX_LPIB),
> -	SND_PCI_QUIRK(0x1106, 0x3288, "ASUS M2V-MX SE", POS_FIX_LPIB),
>  	SND_PCI_QUIRK(0x1297, 0x3166, "Shuttle", POS_FIX_LPIB),
>  	SND_PCI_QUIRK(0x1458, 0xa022, "ga-ma770-ud3", POS_FIX_LPIB),
>  	SND_PCI_QUIRK(0x1462, 0x1002, "MSI Wind U115", POS_FIX_LPIB),
> 
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