Re: [PATCH] siano: make it work again with CONFIG_VMAP_STACK

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Tue, 14 Feb 2017 11:41:46 -0800
Greg KH <gregkh@linuxfoundation.org> escreveu:

> On Tue, Feb 14, 2017 at 05:32:11PM -0200, Mauro Carvalho Chehab wrote:
> > Reported as a Kaffeine bug:
> > 	https://bugs.kde.org/show_bug.cgi?id=375811
> > 
> > The USB control messages require DMA to work. We cannot pass
> > a stack-allocated buffer, as it is not warranted that the
> > stack would be into a DMA enabled area.
> > 
> > On Kernel 4.9, the default is to not accept DMA on stack anymore.
> > 
> > Tested with USB ID 2040:5510: Hauppauge Windham
> > 
> > Cc: stable@vger.kernel.org # For 4.9+  
> 
> Unless there is some major reason, this should go into _all_ stable
> releases, as the driver would be broken on them all for platforms that
> can't handle USB data that is not DMA-able.  This has been a requirement
> for USB drivers since the 2.2 days.

Good point! No, there's no particular reason why not backporting it
to older Kernel releases. I suspect that this particular part of
the driver hasn't changed for a while. So, it can very likely be
backported to all stable releases.

I'll fix the C/C message when submitting it upstream.

Thanks,
Mauro