Subject: [PATCH] USB: set device dma_mask without reference to global data

From: [email-masked] (Arnd Bergmann)
Date: Wed, 8 May 2013 01:42:11 +0200

On Wednesday 08 May 2013, Greg Kroah-Hartman wrote:
> On Tue, May 07, 2013 at 04:53:52PM -0600, Stephen Warren wrote:
> > From: Stephen Warren <[email-masked]>

> > Suggested-by: Arnd Bergmann <[email-masked]>
> > Signed-off-by: Stephen Warren <[email-masked]>
> 
> So this needs to go in for 3.10, right?  Any older kernels as well?  If
> so, which ones?

The fix should definitely go into 3.10, but I'd suggest waiting with
the backport for a couple of -rc releases to avoid possible regressions.
We know that the current code is broken, but few people fully understand
what is going on with coherent_dma_mask, so it might cause new problems
in combination with some other unknown bug, and I don't see this as
urgent: none of the ARM defconfigs build this driver as a loadable
module and there is no bug in the built-in case. For some reason, only
the ARM back-end drivers are broken.

The first occurence was apparently in 3.3, but only in ehci-tegra.c,
while the other drivers subsequently copied the bug.

	Arnd