Hello, On Thu 10-04-14 12:02:50, Marek Szyprowski wrote: > On 2014-03-17 20:49, Jan Kara wrote: > > The following patch series is my first stab at abstracting vma handling > >from the various media drivers. After this patch set drivers have to know > >much less details about vmas, their types, and locking. My motivation for > >the series is that I want to change get_user_pages() locking and I want > >to handle subtle locking details in as few places as possible. > > > >The core of the series is the new helper get_vaddr_pfns() which is given a > >virtual address and it fills in PFNs into provided array. If PFNs correspond to > >normal pages it also grabs references to these pages. The difference from > >get_user_pages() is that this function can also deal with pfnmap, mixed, and io > >mappings which is what the media drivers need. > > > >The patches are just compile tested (since I don't have any of the hardware > >I'm afraid I won't be able to do any more testing anyway) so please handle > >with care. I'm grateful for any comments. > > Thanks for posting this series! I will check if it works with our > hardware soon. This is something I wanted to introduce some time ago to > simplify buffer handling in dma-buf, but I had no time to start working. Thanks for having a look in the series. > However I would like to go even further with integration of your pfn > vector idea. This structure looks like a best solution for a compact > representation of the memory buffer, which should be considered by the > hardware as contiguous (either contiguous in physical memory or mapped > contiguously into dma address space by the respective iommu). As you > already noticed it is widely used by graphics and video drivers. > > I would also like to add support for pfn vector directly to the > dma-mapping subsystem. This can be done quite easily (even with a > fallback for architectures which don't provide method for it). I will try > to prepare rfc soon. This will finally remove the need for hacks in > media/v4l2-core/videobuf2-dma-contig.c That would be a worthwhile thing to do. When I was reading the code this seemed like something which could be done but I delibrately avoided doing more unification than necessary for my purposes as I don't have any hardware to test and don't know all the subtleties in the code... BTW, is there some way to test the drivers without the physical video HW? Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
