V4L/DVB: V4L2: add a generic function to find the nearest discrete format to the...

Many video drivers implement a fixed set of frame formats and thus face a task
of finding the best match for a user-requested format. Implementing this in a
generic function has also an advantage, that different drivers with similar
supported format sets will select the same format for the user, which improves
consistency across drivers.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/v4l2-common.c b/drivers/media/video/v4l2-common.c
index 8ee1179be926ed16d8199e7573ad65c8adb49c23..31ae1a138613c797382666425116d94d824eef44 100644 (file)
--- a/drivers/media/video/v4l2-common.c
+++ b/drivers/media/video/v4l2-common.c
@@ -676,3 +676,27 @@ int v4l_fill_dv_preset_info(u32 preset, struct v4l2_dv_enum_preset *info)
        return 0;
 }
 EXPORT_SYMBOL_GPL(v4l_fill_dv_preset_info);
+
+struct v4l2_frmsize_discrete *v4l2_find_nearest_format(struct v4l2_discrete_probe *probe,
+                                                      s32 width, s32 height)
+{
+       int i;
+       u32 error, min_error = UINT_MAX;
+       struct v4l2_frmsize_discrete *size, *best = NULL;
+
+       if (!probe)
+               return best;
+
+       for (i = 0, size = probe->sizes; i < probe->num_sizes; i++, size++) {
+               error = abs(size->width - width) + abs(size->height - height);
+               if (error < min_error) {
+                       min_error = error;
+                       best = size;
+               }
+               if (!error)
+                       break;
+       }
+
+       return best;
+}
+EXPORT_SYMBOL_GPL(v4l2_find_nearest_format);

diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index b06479f63271276e576a7b5e670a0e724ca2a898..957d5b093847ba42d7f64e6b154c56082f2e3293 100644 (file)
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -397,6 +397,14 @@ struct v4l2_frmsize_discrete {
        __u32                   height;         /* Frame height [pixel] */
 };
 
+struct v4l2_discrete_probe {
+       const struct v4l2_frmsize_discrete      *sizes;
+       int                                     num_sizes;
+};
+
+struct v4l2_frmsize_discrete *v4l2_find_nearest_format(struct v4l2_discrete_probe *probe,
+                                                      s32 width, s32 height);
+
 struct v4l2_frmsize_stepwise {
        __u32                   min_width;      /* Minimum frame width [pixel] */
        __u32                   max_width;      /* Maximum frame width [pixel] */