Dear All,
On 2015-04-02 17:25, Hans Verkuil wrote:
On 04/02/2015 05:02 PM, Jan Kara wrote:
Hello,
On Tue 17-03-15 12:56:30, Jan Kara wrote:
After a long pause I'm sending second version of my patch series to abstract
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.
I have tested the patches with vivid driver so at least vb2 code got some
exposure. Conversion of other drivers was just compile-tested so I'd like to
ask respective maintainers if they could have a look. Also I'd like to ask mm
folks to check patch 2/9 implementing the helper. Thanks!
Ping? Any reactions?
For patch 1/9:
Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
For the other patches I do not feel qualified to give Acks. I've Cc-ed Pawel and
Marek who have a better understanding of the mm internals than I do. Hopefully
they can review the code.
It definitely looks like a good idea, and if nobody else will comment on the vb2
patches in the next 2 weeks, then I'll try to review it myself (for whatever that's
worth).
I'm really sorry that I didn't manage to find time to review this
patchset. I really
like the idea of moving pfn lookup from videobuf2/driver to some common
code in mm
and it is really great that someone managed to provide nice generic code
for it.
I've applied the whole patchset onto v4.0 and tested it on Odroid U3
(with some
additional patches). VideoBuf2-dc works still fine with USERPTR gathered
from other's
device mmaped buffer. You can add my:
Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
for the patches 1-8. Patch 9/9 doesn't apply anymore, so I've skipped
it. Patch 2
needs a small fixup - you need to add '#include <linux/vmalloc.h>',
because otherwise
it doesn't compile. There have been also a minor conflict to be resolved
in patch 7.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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