Re: [PATCH] add raw video support for Samsung SUR40 touchscreen

[Florian Echtler <floe@butterbrot.org>]

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Hello everyone,

On 04.02.2015 12:39, Hans Verkuil wrote:
> On 02/04/15 12:34, Laurent Pinchart wrote:
>> On Wednesday 04 February 2015 11:56:58 Florian Echtler wrote:
>>> That's what I assumed, however, I'm running into the same problem as
>>> with dma-sg when I switch to vmalloc...?
>>
>> I don't expect vmalloc to work, as you can't DMA to vmalloc memory directly 
>> without any IOMMU in the general case (the allocated memory being physically 
>> fragmented).
>>
>> dma-sg should work though, but you won't be able to use usb_bulk_msg(). You 
>> need to create the URBs manually, set their sg and num_sgs fields and submit 
>> them.
Can I also use usb_sg_init/_wait for this? I can't find any other driver
which uses USB in conjunction with dma-sg, can you suggest one I could
use as an example?

> Anyway Florian, based on Laurent's explanation I think trying to make
> dma-sg work seems to be the best solution. And I've learned something
> new :-)
Thanks for the clarification, please ignore the v2 patch submission for
now :-)

Best, Florian
-- 
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