V4L/DVB (12243): em28xx: allow specifying sensor xtal frequency

In order to properly estimate fps, mt9v011 sensor driver needs to know
what is the used frequency on the sensor cristal. Adds the proper fields
and initialization code for specifying the cristal frequency.

Also, based on experimentation, it was noticed that the Silvercrest is
outputing data at 7 fps. This means that it should be using a 6.3 MHz
cristal. This information needs to be double checked later, by opening
the device. Anyway, by using this value for xtal, at least now we have
the correct fps report.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/media/video/em28xx/em28xx.h b/drivers/media/video/em28xx/em28xx.h
index 71444ddbe40c..ce76633786c8 100644
--- a/drivers/media/video/em28xx/em28xx.h
+++ b/drivers/media/video/em28xx/em28xx.h
@@ -478,8 +478,10 @@ struct em28xx {
         struct v4l2_device v4l2_dev;
         struct em28xx_board board;
 
+        /* Webcam specific fields */
         enum em28xx_sensor em28xx_sensor;
         int sensor_xres, sensor_yres;
+        int sensor_xtal;
 
         unsigned int stream_on:1;       /* Locks streams */
         unsigned int has_audio_class:1;