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[media] gspca_pac7311: Properly set the compression balance

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Before this patch sometimes the camera would run out of bandwidth when
running at 640x480@30.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans de Goede 2012-04-27 12:56:59 -03:00 committed by Mauro Carvalho Chehab
parent 4b8ceb6c15
commit 282ddfbcab
1 changed files with 25 additions and 5 deletions
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30
drivers/media/video/gspca/pac7311.c
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@ -29,7 +29,18 @@
* 0x1b Auto white balance related, bit 0 is AWB enable (inverted)
* bits 345 seem to toggle per color gains on/off (inverted)
* 0x78 Global control, bit 6 controls the LED (inverted)
* 0x80 JPEG compression ratio ? Best not touched
* 0x80 Compression balance, interesting settings:
* 0x01 Use this to allow the camera to switch to higher compr.
* on the fly. Needed to stay within bandwidth @ 640x480@30
* 0x1c From usb captures under Windows for 640x480
* 0x2a Values >= this switch the camera to a lower compression,
* using the same table for both luminance and chrominance.
* This gives a sharper picture. Usable only at 640x480@ <
* 15 fps or 320x240 / 160x120. 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
* 0x3f From usb captures under Windows for 320x240
* 0x69 From usb captures under Windows for 160x120
*
* Register page 4:
*
@ -408,12 +419,21 @@ static void setexposure(struct gspca_dev *gspca_dev)
* 640x480 mode and page 4 reg 2 <= 3 then it must be 9
*/
reg_w(gspca_dev, 0xff, 0x01);
if (gspca_dev->cam.cam_mode[(int)gspca_dev->curr_mode].priv &&
sd->ctrls[EXPOSURE].val <= 3) {
if (gspca_dev->width != 640 && sd->ctrls[EXPOSURE].val <= 3)
reg_w(gspca_dev, 0x08, 0x09);
} else {
else
reg_w(gspca_dev, 0x08, 0x08);
}
/*
* Page1 register 80 sets the compression balance, normally we
* want / use 0x1c, but for 640x480@30fps we must allow the
* camera to use higher compression or we may run out of
* bandwidth.
*/
if (gspca_dev->width == 640 && sd->ctrls[EXPOSURE].val == 2)
reg_w(gspca_dev, 0x80, 0x01);
else
reg_w(gspca_dev, 0x80, 0x1c);
/* load registers to sensor (Bit 0, auto clear) */
reg_w(gspca_dev, 0x11, 0x01);