lkml.org 
[lkml]   [2010]   [Oct]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH] add dma_reserve_coherent_memory()/dma_free_reserved_memory() API
On Sun, 10 Oct 2010, Marin Mitov wrote:

> On Sunday, October 10, 2010 05:08:22 pm FUJITA Tomonori wrote:
> > On Fri, 20 Aug 2010 14:50:12 +0300
> > Marin Mitov <mitov@issp.bas.bg> wrote:
> >
> > > On Friday, August 20, 2010 11:35:06 am FUJITA Tomonori wrote:
> > > > On Fri, 20 Aug 2010 11:13:45 +0300
> > > > Marin Mitov <mitov@issp.bas.bg> wrote:
> > > >
> > > > > > > This tric is already used in drivers/staging/dt3155v4l.c
> > > > > > > dt3155_alloc_coherent()/dt3155_free_coherent()
> > > > > > >
> > > > > > > Here proposed for general use by popular demand from video4linux folks.
> > > > > > > Helps for videobuf-dma-contig framework.
> > > > > >
> > > > > > What you guys exactly want to do? If you just want to pre-allocate
> > > > > > coherent memory for latter usage,
> > > > >
> > > > > Yes, just to preallocate not coherent, but rather contiguous memory for latter usage.
> > > > > We use coherent memory because it turns out to be contiguous.
> > > >
> > > > Hmm, you don't care about coherency? You just need contiguous memory?
> > >
> > > Yes. We just need contiguous memory. Coherency is important as far as when dma
> > > transfer finishes user land is able to see the new data. Could be done by something like
> > > dma_{,un}map_single()
> >
> > Anyone is working on this?
>
> I am not, sorry.
>
> >
> > KAMEZAWA posted a patch to improve the generic page allocator to
> > allocate physically contiguous memory. He said that he can push it
> > into mainline.
>
> I am waiting for the new videobuf2 framework to become part of the kernel.
> Then KAMEZAWA's improvements can help.

You probably have seen this related thread:
http://marc.info/?t=128644473600004&r=1&w=2

Thanks
Guennadi

> Marin Mitov
>
> >
> > The approach enables us to solve this issue without adding any new
> > API.
> >
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/


\
 
 \ /
  Last update: 2010-10-10 20:23    [W:0.309 / U:0.676 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site