Hi Am 18.02.21 um 16:07 schrieb Christoph Hellwig:
On Thu, Feb 18, 2021 at 03:56:00PM +0100, Thomas Zimmermann wrote:I only have udl devices, but I expect that other DRM USB adapters are also affected.Find where the driver calls dma_map_* itself instead of using the USB wrappers and fix that..
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?
Best regards Thomas[1] https://elixir.bootlin.com/linux/v5.11/source/drivers/gpu/drm/drm_prime.c#L630
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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