RE: dma_alloc_coherent fragmentation

["Shilimkar, Santosh" <santosh.shilimkar@ti.com>]

This would just temporarily delay the problem. People have even tried with values of 14 MB and all. Nishant M knows one such recent issue.

Bye the way use of this macro for general DMAable memory is discouraged. You can find many threads on ARM mailing list. 

Regards,
Santosh
 

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org 
> [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of pramod gurav
> Sent: Wednesday, April 22, 2009 3:14 PM
> To: Gupta, Ramesh
> Cc: Menon, Nishanth; linux-omap@vger.kernel.org
> Subject: Re: dma_alloc_coherent fragmentation
> 
> Hi Ramesh,
> This worked. Thanks a lot.
> 
> 
> -- 
> Best Regards
> Pramod
> 
> 
> On Wed, Apr 22, 2009 at 2:44 PM, Gupta, Ramesh <grgupta@ti.com> wrote:
> > Hi Pramod,
> >
> >
> >> -----Original Message-----
> >> From: linux-omap-owner@vger.kernel.org
> >> [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of pramod gurav
> >> Sent: Wednesday, April 22, 2009 1:17 PM
> >> To: Menon, Nishanth
> >> Cc: linux-omap@vger.kernel.org
> >> Subject: Re: dma_alloc_coherent fragmentation
> >>
> >> Hi Nishant,
> >> I am facing the same problem to allocate a chunk of 4MB on omap3evm
> >> using dma_alloc_coherent. I used the test driver mentioned here
> >> 
> http://www.mail-archive.com/linux-omap@vger.kernel.org/msg11074.html
> >>
> >> I applied the patch for
> >> ioremap(24f11ec001920f1cfaeeed8e8b55725d900bbb56) suggested by
> >> Russell, but stiill seeing the error saying
> >>
> >> coherent allocation too big (requested 0x400000 mask 0xffffffff)
> >> alloc[0] - virt=0x00000000 phy=0xFFFFFFFF size=0x00400000
> >> Allocation failed idx=0
> >> insmod: cannot insert `dummy.ko': Cannot allocate memory 
> (-1): Cannot
> >> allocate memory
> >>
> >> I changed the GFP_KERNEL to GFP_TEMPORARY and also to (GFP_KERNEL |
> >> __GFP_RECLAIMABLE), but failed to insmod the module.
> >> I am working on linux-omap 2.6.28 kernel. Even I could not allocate
> >> memory size greater than 1MB.
> >> Has this been fixed? Are there any patches to fix this issue?
> >>
> >
> > What is the value for 'CONFIG_FB_OMAP_CONSISTENT_DMA_SIZE' 
> (default is 2 in omap_3430sdp_defconfig), Can you please
> > try increasing to 8?
> >
> > Regards
> > Ramesh Gupta G
> >
> --
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