Hi Am 15.02.21 um 09:58 schrieb Christian König:
Hi guys,we are currently working an Freesync and direct scan out from system memory on AMD APUs in A+A laptops.On problem we stumbled over is that our display hardware needs to scan out from uncached system memory and we currently don't have a way to communicate that through DMA-buf.For our specific use case at hand we are going to implement something driver specific, but the question is should we have something more generic for this?
For vmap operations, we return the address as struct dma_buf_map, which contains additional information about the memory buffer. In vram helpers, we have the interface drm_gem_vram_offset() that returns the offset of the GPU device memory.
Would it be feasible to combine both concepts into a dma-buf interface that returns the device-memory offset plus the additional caching flag?
There'd be a structure and a getter function returning the structure.
struct dma_buf_offset {
bool cached;
u64 address;
};
// return offset in *off
int dma_buf_offset(struct dma_buf *buf, struct dma_buf_off *off);
Whatever settings are returned by dma_buf_offset() are valid while the
dma_buf is pinned.
Best regards Thomas
After all the system memory access pattern is a PCIe extension and as such something generic.Regards, Christian. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 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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