Re: [PATCH]: x86_64, audio: Fix system panic when DMA > 40 bits

[David Henningsson]

On 05/02/2013 08:36 AM, Mike Travis wrote:
> On 5/1/2013 11:20 PM, David Henningsson wrote:
> > On 05/01/2013 09:04 PM, Mike Travis wrote:
> > > The audio driver mistakenly allows 64 bit addresses to be created for
> > > the audio driver on Nvidia GPUs.  Unfortunately, the hardware normally
> > > only supports up to 40 bits of DMA.  This can cause system panics as
> > > well as misdirected data when the address is > 40 bits as the upper
> > > part the address is truncated.
> >
> > Thanks for this patch. Stephen Warren, is this something you can
> > confirm/deny, and do you know what range of hardware this actually
> > applies to?
>
> The dma_mask can be read from the gpu device's pci entry.  I know it's
> a stretch to try to link to that but past history has shown that it
> ranges from 36 to 40 bits.

Ok, so the below patch is some kind of workaround, as we don't currently 
take the dma_mask into account correctly? Or put in another way, would 
it be possible/better to actually read the dma_mask and use that instead 
of just clamping at 32 bit?

> > > Signed-off-by: Mike Travis <travis@xxxxxxx>
> > > Reviewed-by: Mike Habeck <habeck@xxxxxxx>
> > > ---
> > >    sound/pci/hda/hda_intel.c | 2 +-
> > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > > index bcd40ee..45eb165 100644
> > > --- a/sound/pci/hda/hda_intel.c
> > > +++ b/sound/pci/hda/hda_intel.c
> > > @@ -615,7 +615,7 @@ enum {
> > >    /* quirks for Nvidia */
> > >    #define AZX_DCAPS_PRESET_NVIDIA \
> > >        (AZX_DCAPS_NVIDIA_SNOOP | AZX_DCAPS_RIRB_DELAY |
> > > AZX_DCAPS_NO_MSI |\
> > > -     AZX_DCAPS_ALIGN_BUFSIZE)
> > > +     AZX_DCAPS_ALIGN_BUFSIZE | AZX_DCAPS_NO_64BIT)
> > >
> > >    #define AZX_DCAPS_PRESET_CTHDA \
> > >        (AZX_DCAPS_NO_MSI | AZX_DCAPS_POSFIX_LPIB |
> > > AZX_DCAPS_4K_BDLE_BOUNDARY)



--
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic
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