1 files changed, 116 insertions, 0 deletions
diff --git a/drivers/media/video/gspca/coarse_expo_autogain.h b/drivers/media/video/gspca/coarse_expo_autogain.h
new file mode 100644
index 000000000000..1cb9d941eaf6
--- /dev/null
+++ b/drivers/media/video/gspca/coarse_expo_autogain.h
@@ -0,0 +1,116 @@
+/*
+ * Auto gain algorithm for camera's with a coarse exposure control
+ *
+ * Copyright (C) 2010 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* Autogain + exposure algorithm for cameras with a coarse exposure control
+   (usually this means we can only control the clockdiv to change exposure)
+   As changing the clockdiv so that the fps drops from 30 to 15 fps for
+   example, will lead to a huge exposure change (it effectively doubles),
+   this algorithm normally tries to only adjust the gain (between 40 and
+   80 %) and if that does not help, only then changes exposure. This leads
+   to a much more stable image then using the knee algorithm which at
+   certain points of the knee graph will only try to adjust exposure,
+   which leads to oscilating as one exposure step is huge.
+
+   Note this assumes that the sd struct for the cam in question has
+   exp_too_high_cnt and exp_too_high_cnt int members for use by this function.
+
+   Returns 0 if no changes were made, 1 if the gain and or exposure settings
+   where changed. */
+static int gspca_coarse_grained_expo_autogain(struct gspca_dev *gspca_dev,
+	int avg_lum, int desired_avg_lum, int deadzone)
+{
+	int i, steps, gain, orig_gain, exposure, orig_exposure;
+	int gain_low, gain_high;
+	const struct ctrl *gain_ctrl = NULL;
+	const struct ctrl *exposure_ctrl = NULL;
+	struct sd *sd = (struct sd *) gspca_dev;
+	int retval = 0;
+
+	for (i = 0; i < gspca_dev->sd_desc->nctrls; i++) {
+		if (gspca_dev->ctrl_dis & (1 << i))
+			continue;
+		if (gspca_dev->sd_desc->ctrls[i].qctrl.id == V4L2_CID_GAIN)
+			gain_ctrl = &gspca_dev->sd_desc->ctrls[i];
+		if (gspca_dev->sd_desc->ctrls[i].qctrl.id == V4L2_CID_EXPOSURE)
+			exposure_ctrl = &gspca_dev->sd_desc->ctrls[i];
+	}
+	if (!gain_ctrl || !exposure_ctrl) {
+		PDEBUG(D_ERR, "Error: gspca_coarse_grained_expo_autogain "
+			"called on cam without gain or exposure");
+		return 0;
+	}
+
+	if (gain_ctrl->get(gspca_dev, &gain) ||
+	    exposure_ctrl->get(gspca_dev, &exposure))
+		return 0;
+
+	orig_gain = gain;
+	orig_exposure = exposure;
+	gain_low =
+		(gain_ctrl->qctrl.maximum - gain_ctrl->qctrl.minimum) / 5 * 2;
+	gain_low += gain_ctrl->qctrl.minimum;
+	gain_high =
+		(gain_ctrl->qctrl.maximum - gain_ctrl->qctrl.minimum) / 5 * 4;
+	gain_high += gain_ctrl->qctrl.minimum;
+
+	/* If we are of a multiple of deadzone, do multiple steps to reach the
+	   desired lumination fast (with the risc of a slight overshoot) */
+	steps = (desired_avg_lum - avg_lum) / deadzone;
+
+	PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d",
+		avg_lum, desired_avg_lum, steps);
+
+	if ((gain + steps) > gain_high &&
+	    sd->exposure < exposure_ctrl->qctrl.maximum) {
+		gain = gain_high;
+		sd->exp_too_low_cnt++;
+	} else if ((gain + steps) < gain_low &&
+		   sd->exposure > exposure_ctrl->qctrl.minimum) {
+		gain = gain_low;
+		sd->exp_too_high_cnt++;
+	} else {
+		gain += steps;
+		if (gain > gain_ctrl->qctrl.maximum)
+			gain = gain_ctrl->qctrl.maximum;
+		else if (gain < gain_ctrl->qctrl.minimum)
+			gain = gain_ctrl->qctrl.minimum;
+		sd->exp_too_high_cnt = 0;
+		sd->exp_too_low_cnt = 0;
+	}
+
+	if (sd->exp_too_high_cnt > 3) {
+		exposure--;
+		sd->exp_too_high_cnt = 0;
+	} else if (sd->exp_too_low_cnt > 3) {
+		exposure++;
+		sd->exp_too_low_cnt = 0;
+	}
+
+	if (gain != orig_gain) {
+		gain_ctrl->set(gspca_dev, gain);
+		retval = 1;
+	}
+	if (exposure != orig_exposure) {
+		exposure_ctrl->set(gspca_dev, exposure);
+		retval = 1;
+	}
+
+	return retval;
+}