Re: [PATCH v3 2/4] videobuf2-dma-streaming: new videobuf2 memory allocator

[Alessandro Rubini <rubini@gnudd.com>]

> The problem is that on the sta2x11 architecture only the first 
> 512MB are available through the PCI bus, but the allocator can allocate memory 
> for DMA above this limit. By using GFP_DMA flags the allocation take place 
> under the 16MB so it works.

Still, you are not running the upstream allocator.  IIUC, you added a
"gfp_t" field in the platform data or somewhere, so the sta2x11 can
request GFP_DMA to be OR'd, while other users remain unaffected.  Will
you please submit the patch to achieve that?

> I cannot do performance test at the moment because I don't have the time, so I 
> cannot personally justify the presence of a new allocator.

I don't expect you'll see serious performance differences on the PC. I
think ARM users will have better benefits, due to the different cache
architecture.  You told me Jon measured meaningful figures on a Marvel
CPU.

> I will propose V4 patches soon.

thanks
/alessandro