ov2640: fix vflip control

commit 7f140fc2064bcd23e0490d8210650e2ef21c1c89 upstream.

Enabling vflip currently causes wrong colors.
It seems that (at least with the current sensor setup) REG04_VFLIP_IMG only
changes the vertical readout direction.
Because pixels are arranged RGRG... in odd lines and GBGB... in even lines,
either a one line shift or even/odd line swap is required, too, but
apparently this doesn't happen.

I finally figured out that this can be done manually by setting
REG04_VREF_EN.
Looking at hflip, it turns out that bit REG04_HREF_EN is set there
permanetly, but according to my tests has no effect on the pixel readout
order.
So my conclusion is that the current documentation of sensor register 0x04
is wrong (has changed after preliminary datasheet version 2.2).

I'm pretty sure that automatic vertical line shift/switch can be enabled,
too, but until anyone finds ot how this works, we have to stick with manual
switching.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/media/video/ov2640.c b/drivers/media/video/ov2640.c
index b5247cb64fdea1510774e48cbddf3b68f4508abb..ca721b719c144d9bc074e92f39c897c4def4985a 100644 (file)
--- a/drivers/media/video/ov2640.c
+++ b/drivers/media/video/ov2640.c
@@ -687,8 +687,10 @@ static int ov2640_s_ctrl(struct v4l2_ctrl *ctrl)
 
        switch (ctrl->id) {
        case V4L2_CID_VFLIP:
-               val = ctrl->val ? REG04_VFLIP_IMG : 0x00;
-               return ov2640_mask_set(client, REG04, REG04_VFLIP_IMG, val);
+               val = ctrl->val ? REG04_VFLIP_IMG | REG04_VREF_EN : 0x00;
+               return ov2640_mask_set(client, REG04,
+                                      REG04_VFLIP_IMG | REG04_VREF_EN, val);
+               /* NOTE: REG04_VREF_EN: 1 line shift / even/odd line swap */
        case V4L2_CID_HFLIP:
                val = ctrl->val ? REG04_HFLIP_IMG : 0x00;
                return ov2640_mask_set(client, REG04, REG04_HFLIP_IMG, val);