[media] gspca_pac7302: Document some more registers

Note like all info on the pac73xx chips, this info was found by trial and
error, so it is not necessarily 100% correct.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/media/video/gspca/pac7302.c b/drivers/media/video/gspca/pac7302.c
index 1e88d3a574d9..a2a42f61d3c0 100644
--- a/drivers/media/video/gspca/pac7302.c
+++ b/drivers/media/video/gspca/pac7302.c
@@ -30,6 +30,14 @@
  *
  * Address      Description
  * 0x78         Global control, bit 6 controls the LED (inverted)
+ * 0x80         Compression balance, 2 interesting settings:
+ *              0x0f Default
+ *              0x50 Values >= this switch the camera to a lower compression,
+ *                   using the same table for both luminance and chrominance.
+ *                   This gives a sharper picture. Only usable when running
+ *                   at < 15 fps! Note currently the driver does not use this
+ *                   as the quality gain is small and the generated JPG-s are
+ *                   only understood by v4l-utils >= 0.8.9
  *
  * Register page 3:
  *
@@ -43,8 +51,14 @@
  *              1 -> ~30 fps, 2 -> ~20 fps
  * 0x0e         Exposure bits 0-7, 0-448, 0 = use full frame time
  * 0x0f         Exposure bit 8, 0-448, 448 = no exposure at all
- * 0x10         Master gain 0-31
+ * 0x10         Gain 0-31
+ * 0x12         Another gain 0-31, unlike 0x10 this one seems to start with an
+ *              amplification value of 1 rather then 0 at its lowest setting
  * 0x21         Bitfield: 0-1 unused, 2-3 vflip/hflip, 4-5 unknown, 6-7 unused
+ * 0x80         Another framerate control, best left at 1, moving it from 1 to
+ *              2 causes the framerate to become 3/4th of what it was, and
+ *              also seems to cause pixel averaging, resulting in an effective
+ *              resolution of 320x240 and thus a much blockier image
  *
  * The registers are accessed in the following functions:
  *