lkml.org 
[lkml]   [2013]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v4 1/3] videobuf2-dma-contig: user can specify GFP flags
Date
> > @@ -165,7 +161,8 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned
> > long size)>
> > /* align image size to PAGE_SIZE */
> > size = PAGE_ALIGN(size);
> >
> > - buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
GFP_KERNEL);
> > + buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
> > +
GFP_KERNEL | conf->mem_flags);
>
> I think we can add GFP_DMA flag unconditionally to the vb2_dc_contig
> allocator.
> It won't hurt existing clients as most of nowadays platforms doesn't
> have DMA
> zone (GFP_DMA is ignored in such case), but it should fix the issues
> with some
> older and non-standard systems.

I did not set GFP_DMA fixed in the allocator because I do not want to brake
something in the future. On x86 platform GFP_DMA allocates under 16MB and this
limit can be too strict. When many other drivers use GFP_DMA we can saturate
this tiny zone.
As you said, this fix the issue with _older_ and _non-standard_ (like sta2x11)
systems. But this fix has effect on every other standard and new systems.
That's why I preferred to set the flag optionally.

--
Federico Vaga


\
 
 \ /
  Last update: 2013-01-08 12:41    [W:0.076 / U:0.616 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site