[PATCH v2] clients: teach simple-dmabuf-v4l to deal with flipped input

[Pekka Paalanen]

On Tue, 7 Feb 2017 17:17:41 -0800
Bryce Harrington <bryce at osg.samsung.com> wrote:

> On Tue, Feb 07, 2017 at 11:48:47AM +0200, Pekka Paalanen wrote:
> > On Mon,  6 Feb 2017 12:57:41 -0500
> > Micah Fedke <micah.fedke at collabora.co.uk> wrote:
> >   
> > > The v4l2 API can be queried to detect if the input video image is
> > > horizontally or vertically flipped. If the image is y-flipped, we can
> > > set the ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_Y_INVERT flag to notify the
> > > compositor.  If the image is h-flipped, we can only print a warning
> > > since linux_buffer_params_v1 does not support horizontal flipping.
> > > 
> > > Signed-off-by: Micah Fedke <micah.fedke at collabora.co.uk>
> > > ---
> > > This version addresses Pekka's comments by renaming check_v4l2_control to
> > > check_v4l2_control_bool, removing the len parameter, separating out the logic
> > > tests in check_v4l2_control_bool and fixing spacing issues.
> > > 
> > >  clients/simple-dmabuf-v4l.c | 62 +++++++++++++++++++++++++++++++++++++++------
> > >  1 file changed, 54 insertions(+), 8 deletions(-)  
> > 
> > Hi,
> > 
> > looks fine, pushed with my R-b:
> >    9a200d7..0fee977  master -> master  
> 
> Breaks the build on older linux kernels.
> 
>   CC       clients/weston_simple_dmabuf_v4l-simple-dmabuf-v4l.o
> clients/simple-dmabuf-v4l.c:358:25: warning: ‘struct v4l2_query_ext_ctrl’ declared inside parameter list [enabled by default]
>                          const int expected_value)
>                          ^
> clients/simple-dmabuf-v4l.c:358:25: warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]
> clients/simple-dmabuf-v4l.c: In function ‘check_v4l2_control_bool’:
> clients/simple-dmabuf-v4l.c:363:18: error: dereferencing pointer to incomplete type
>   ctrl.id = qectrl->id;
>                   ^
> et al.
> 
> Builds ok with the patch reverted, or with --disable-simple-dmabuf-v4l-client set.
> 

Hi,

reverting is fine by me, and if you really want, reapplying this patch
can also be delayed for the next development cycle.

It looks like ext_ctrl was introduced in

commit 5082c2417841e64df975789011e182ce99a9dacd
Author: Hans Verkuil <hans.verkuil at cisco.com>
Date:   Tue Jun 10 04:14:50 2014 -0300

    [media] videodev2.h: add struct v4l2_query_ext_ctrl and VIDIOC_QUERY_EXT_CTRL

which was first released in 3.17.

I wonder, the commit seems to say this is just an extended way of
getting attributes. Is there an older method exposing the
attributes we need?

If there is, I'd prefer we use that. If not, then we need #ifdef
VIDIOC_QUERY_EXT_CTRL. I'm also fine with going just the #ifdef route
directly.

Micah?


Thanks,
pq
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