Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tuesday 10 November 2015 11:00:59 Timur Tabi wrote:
> On 11/10/2015 10:47 AM, Arnd Bergmann wrote:
> > What BenH was worried about here is that the driver sets different masks
> > for streaming and coherent mappings, which is indeed a worry that
> > could hit us on ARM as well, but I suppose we'll have to deal with
> > that in platform code.
> >
> > Setting both masks to 32-bit is something that a lot of drivers do,
> > and without IOMMU enabled, you'd hit the same bug on all of them.
> 
> Also note that I think that on PowerPC, the mask is set to 32 by default 
> for all devices.  I don't think we do that on ARM64.  So on PowerPC, 
> some drivers get away with not explicitly setting the mask.
> 

If the mask is 64-bit by default on ARM64, that is a bug that we need
to fix urgently. Can you verify this?

A lot of PCI devices can only do 32-bit DMA, and we have plenty
of drivers that don't bother setting a mask at all because the 32-bit
mask is the default on all other architectures.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux