[alsa-devel] [PATCH 1/2] ALSA: hda - Fix probing and stuttering on CMI8888 HD-audio controller

[Geoffrey McRae]

I can confirm that disable of MSI is required as even Windows 7
64bit does not enable this for Intel HDA. Out of curiosity I altered
the driver to use MSI-X with the same results, interrupts are never
received even though the PCI caps state that MSI is supported.

Playback is very poor and stutters if I do not allow snoop by
commenting out "case AZX_DRIVER_CMEDIA:" in azx_check_snoop_available.

I can also confirm that AZX_DCAPS_POSFIX_LPIB is required on my
hardware also.

http://www.alsa-project.org/db/?f=512e0135e82a644bb9d2fe8f6b5e2be1cb10c53b

Things of note:

ASUS Sabertooth 990FX r1 with bugged IOMMU
Linux does not load correctly without IOMMU enabled, so disabling to
test is not an option.

On Wed,  6 Aug 2014 14:39:14 +0200
Takashi Iwai <tiwai at suse.de> wrote:

> ASUS Phoebus with CMI8888 HD-audio chip (PCI id 13f6:5011) doesn't
> work with HD-audio driver as is because of some weird nature.  For
> making DMA properly working, we need to disable MSI.  The position
> report buffer doesn't work, thus we need to force reading LPIB
> instead.  And yet, the codec CORB/RIRB communication gives errors
> unless we disable the snooping (caching).
> 
> In this patch, all these workarounds are added as a quirk for the
> device.  The HD-audio *codec* chip needs yet another workaround, but
> it'll be provided in the succeeding patch.
> 
> Reported-and-tested-by: Vincent Lejeune <vljn at ovi.com>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> ---
>  sound/pci/hda/hda_intel.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 5db1948699d8..aa302fb03fc5 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -265,6 +265,7 @@ enum {
>  	AZX_DRIVER_TERA,
>  	AZX_DRIVER_CTX,
>  	AZX_DRIVER_CTHDA,
> +	AZX_DRIVER_CMEDIA,
>  	AZX_DRIVER_GENERIC,
>  	AZX_NUM_DRIVERS, /* keep this as last entry */
>  };
> @@ -330,6 +331,7 @@ static char *driver_short_names[] = {
>  	[AZX_DRIVER_TERA] = "HDA Teradici", 
>  	[AZX_DRIVER_CTX] = "HDA Creative", 
>  	[AZX_DRIVER_CTHDA] = "HDA Creative",
> +	[AZX_DRIVER_CMEDIA] = "HDA C-Media",
>  	[AZX_DRIVER_GENERIC] = "HD-Audio Generic",
>  };
>  
> @@ -1373,6 +1375,7 @@ static void azx_check_snoop_available(struct
> azx *chip) snoop = false;
>  		break;
>  	case AZX_DRIVER_CTHDA:
> +	case AZX_DRIVER_CMEDIA:
>  		snoop = false;
>  		break;
>  	}
> @@ -2154,6 +2157,10 @@ static const struct pci_device_id azx_ids[] = {
>  	  .driver_data = AZX_DRIVER_CTX | AZX_DCAPS_CTX_WORKAROUND |
>  	  AZX_DCAPS_RIRB_PRE_DELAY | AZX_DCAPS_POSFIX_LPIB },
>  #endif
> +	/* CM8888 */
> +	{ PCI_DEVICE(0x13f6, 0x5011),
> +	  .driver_data = AZX_DRIVER_CMEDIA |
> +	  AZX_DCAPS_NO_MSI | AZX_DCAPS_POSFIX_LPIB },
>  	/* Vortex86MX */
>  	{ PCI_DEVICE(0x17f3, 0x3010), .driver_data =
> AZX_DRIVER_GENERIC }, /* VMware HDAudio */