On 26/07/2019 08:42, Tomasz Figa wrote:
On Fri, Jul 26, 2019 at 4:41 PM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
On Fri, Jul 26, 2019 at 02:15:14PM +0900, Tomasz Figa wrote:
Could you try dma_get_sgtable() with the SCP struct device and then
dma_map_sg() with the P1 struct device?
Please don't do that. dma_get_sgtable is a pretty broken API (see
the common near the arm implementation) and we should not add more
users of it. If you want a piece of memory that can be mapped to
multiple devices allocate it using alloc_pages and then just map
it to each device.
Thanks for taking a look at this thread.
Unfortunately that wouldn't work. We have a specific reserved memory
pool that is the only memory area accessible to one of the devices.
Any idea how to handle this?
If it's reserved in the sense of being outside struct-page-backed
"kernel memory", then provided you have a consistent CPU physical
address it might be reasonable for other devices to access it via
dma_map_resource().
Robin.
