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Commit 282ddfbc authored by Hans de Goede's avatar Hans de Goede Committed by Mauro Carvalho Chehab
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[media] gspca_pac7311: Properly set the compression balance 



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

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 4b8ceb6c

drivers/media/video/gspca/pac7311.c

+25 −5
Original line number Diff line number Diff line
@@ -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);