Messages in this thread | | | Date | Thu, 18 Feb 2021 16:24:25 +0100 | From | Christoph Hellwig <> | Subject | Re: Regression: 6eb0233ec2d0 ("usb: don't inherity DMA properties for USB devices") |
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On Thu, Feb 18, 2021 at 04:21:26PM +0100, Thomas Zimmermann wrote: > Sure, it's at [1]. For udl, the dmabuf would need to be in system memory. > The driver creates urbs from the framebuffer content and sends them to the > device for displaying. > > My question is more: what's the best interface to do this? Is there example > code somewhere?
URBs do point to system memory most of the time. I'm not a real USB expert, but usb-storage or uas would be classic examples for drivers that take arbitrary memory controller by another layer and do DMA to/from that.
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