On Thu 10-04-14 14:22:20, Hans Verkuil wrote: > On 04/10/14 14:15, Jan Kara wrote: > > On Thu 10-04-14 13:07:42, Hans Verkuil wrote: > >> On 04/10/14 12:32, Jan Kara wrote: > >>> 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? > >> > >> You can use the vivi driver (drivers/media/platform/vivi) for this. > >> However, while the vivi driver can import dma buffers it cannot export > >> them. If you want that, then you have to use this tree: > >> > >> http://git.linuxtv.org/cgit.cgi/hverkuil/media_tree.git/log/?h=vb2-part4 > > Thanks for the pointer that looks good. I've also found > > drivers/media/platform/mem2mem_testdev.c which seems to do even more > > testing of the area I made changes to. So now I have to find some userspace > > tool which can issue proper ioctls to setup and use the buffers and I can > > start testing what I wrote :) > > Get the v4l-utils.git repository (http://git.linuxtv.org/cgit.cgi/v4l-utils.git/). > You want the v4l2-ctl tool. Don't use the version supplied by your distro, > that's often too old. > > 'v4l2-ctl --help-streaming' gives the available options for doing streaming. > > So simple capturing from vivi is 'v4l2-ctl --stream-mmap' or '--stream-user'. > You can't test dmabuf unless you switch to the vb2-part4 branch of my tree. Great, it seems to be doing something and it shows there's some bug in my code. Thanks a lot for help. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>