On 04/11/2014 12:18 AM, Jan Kara wrote: > On Thu 10-04-14 23:57:38, Jan Kara wrote: >> 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. > OK, so after a small fix the basic functionality seems to be working. It > doesn't seem there's a way to test multiplanar buffers with vivi, is there? For that you need to switch to the vb2-part4 branch as well. That has support for multiplanar. Regards, Hans -- 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>