lkml.org 
[lkml]   [2014]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v7 3/8] arm64: introduce is_device_dma_coherent
On Mon, 3 Nov 2014, Will Deacon wrote:
> On Mon, Nov 03, 2014 at 10:46:03AM +0000, Stefano Stabellini wrote:
> > On Mon, 27 Oct 2014, Stefano Stabellini wrote:
> > > Introduce a boolean flag and an accessor function to check whether a
> > > device is dma_coherent. Set the flag from set_arch_dma_coherent_ops.
> > >
> > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> > > CC: will.deacon@arm.com
> >
> > Will, Catalin,
> > are you OK with this patch?
>
> It would be nicer if the dma_coherent flag didn't have to be duplicated by
> each architecture in dev_archdata. Is there any reason not to put it in the
> core code?

Yes, there is a reason for it: if I added a boolean dma_coherent flag in
struct device as Catalin initially suggested, what would be the default
for each architecture? Where would I set it for arch that don't use
device tree? It is not easy.

I thought it would be better to introduce is_device_dma_coherent only on
the architectures where it certainly makes sense to have it. In fact I
checked and arm and arm64 are the only architectures to define
set_arch_dma_coherent_ops at the moment. At that point if
is_device_dma_coherent becomes arch-specific, it makes sense to store
the flag in dev_archdata instead of struct device.


\
 
 \ /
  Last update: 2014-11-03 12:41    [W:0.093 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site