[media] gspca: Add autogain functions for use with control framework drivers

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

drivers/media/video/gspca/Makefile

@@ -43,7 +43,7 @@ obj-$(CONFIG_USB_GSPCA_VICAM)    += gspca_vicam.o
 obj-$(CONFIG_USB_GSPCA_XIRLINK_CIT) += gspca_xirlink_cit.o
 obj-$(CONFIG_USB_GSPCA_ZC3XX)    += gspca_zc3xx.o
 
-gspca_main-objs     := gspca.o
+gspca_main-objs     := gspca.o autogain_functions.o
 gspca_benq-objs     := benq.o
 gspca_conex-objs    := conex.o
 gspca_cpia1-objs    := cpia1.o

drivers/media/video/gspca/autogain_functions.c

@@ -0,0 +1,178 @@
+/*
+ * Functions for auto gain.
+ *
+ * Copyright (C) 2010-2012 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
+ */
+#include "gspca.h"
+
+/* auto gain and exposure algorithm based on the knee algorithm described here:
+   http://ytse.tricolour.net/docs/LowLightOptimization.html
+
+   Returns 0 if no changes were made, 1 if the gain and or exposure settings
+   where changed. */
+int gspca_expo_autogain(
+			struct gspca_dev *gspca_dev,
+			int avg_lum,
+			int desired_avg_lum,
+			int deadzone,
+			int gain_knee,
+			int exposure_knee)
+{
+	s32 gain, orig_gain, exposure, orig_exposure;
+	int i, steps, retval = 0;
+
+	if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0)
+	        return 0;
+
+	orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain);
+	orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure);
+
+	/* 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 = abs(desired_avg_lum - avg_lum) / deadzone;
+
+	PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d",
+		avg_lum, desired_avg_lum, steps);
+
+	for (i = 0; i < steps; i++) {
+		if (avg_lum > desired_avg_lum) {
+			if (gain > gain_knee)
+				gain--;
+			else if (exposure > exposure_knee)
+				exposure--;
+			else if (gain > gspca_dev->gain->default_value)
+				gain--;
+			else if (exposure > gspca_dev->exposure->minimum)
+				exposure--;
+			else if (gain > gspca_dev->gain->minimum)
+				gain--;
+			else
+				break;
+		} else {
+			if (gain < gspca_dev->gain->default_value)
+				gain++;
+			else if (exposure < exposure_knee)
+				exposure++;
+			else if (gain < gain_knee)
+				gain++;
+			else if (exposure < gspca_dev->exposure->maximum)
+				exposure++;
+			else if (gain < gspca_dev->gain->maximum)
+				gain++;
+			else
+				break;
+		}
+	}
+
+	if (gain != orig_gain) {
+	        v4l2_ctrl_s_ctrl(gspca_dev->gain, gain);
+		retval = 1;
+	}
+	if (exposure != orig_exposure) {
+	        v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure);
+		retval = 1;
+	}
+
+	if (retval)
+		PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d",
+			gain, exposure);
+	return retval;
+}
+EXPORT_SYMBOL(gspca_expo_autogain);
+
+/* 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.
+
+   Returns 0 if no changes were made, 1 if the gain and or exposure settings
+   where changed. */
+int gspca_coarse_grained_expo_autogain(
+			struct gspca_dev *gspca_dev,
+			int avg_lum,
+			int desired_avg_lum,
+			int deadzone)
+{
+	s32 gain_low, gain_high, gain, orig_gain, exposure, orig_exposure;
+	int steps, retval = 0;
+
+	if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0)
+	        return 0;
+
+	orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain);
+	orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure);
+
+	gain_low  = (gspca_dev->gain->maximum - gspca_dev->gain->minimum) /
+		    5 * 2 + gspca_dev->gain->minimum;
+	gain_high = (gspca_dev->gain->maximum - gspca_dev->gain->minimum) /
+		    5 * 4 + gspca_dev->gain->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 &&
+	    exposure < gspca_dev->exposure->maximum) {
+		gain = gain_high;
+		gspca_dev->exp_too_low_cnt++;
+		gspca_dev->exp_too_high_cnt = 0;
+	} else if ((gain + steps) < gain_low &&
+		   exposure > gspca_dev->exposure->minimum) {
+		gain = gain_low;
+		gspca_dev->exp_too_high_cnt++;
+		gspca_dev->exp_too_low_cnt = 0;
+	} else {
+		gain += steps;
+		if (gain > gspca_dev->gain->maximum)
+			gain = gspca_dev->gain->maximum;
+		else if (gain < gspca_dev->gain->minimum)
+			gain = gspca_dev->gain->minimum;
+		gspca_dev->exp_too_high_cnt = 0;
+		gspca_dev->exp_too_low_cnt = 0;
+	}
+
+	if (gspca_dev->exp_too_high_cnt > 3) {
+		exposure--;
+		gspca_dev->exp_too_high_cnt = 0;
+	} else if (gspca_dev->exp_too_low_cnt > 3) {
+		exposure++;
+		gspca_dev->exp_too_low_cnt = 0;
+	}
+
+	if (gain != orig_gain) {
+	        v4l2_ctrl_s_ctrl(gspca_dev->gain, gain);
+		retval = 1;
+	}
+	if (exposure != orig_exposure) {
+	        v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure);
+		retval = 1;
+	}
+
+	if (retval)
+		PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d",
+			gain, exposure);
+	return retval;
+}
+EXPORT_SYMBOL(gspca_coarse_grained_expo_autogain);

drivers/media/video/gspca/gspca.h

@@ -6,6 +6,7 @@
 #include <linux/usb.h>
 #include <linux/videodev2.h>
 #include <media/v4l2-common.h>
+#include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
 #include <linux/mutex.h>
 
@@ -174,6 +175,15 @@ struct gspca_dev {
 	unsigned ctrl_dis;		/* disabled controls (bit map) */
 	unsigned ctrl_inac;		/* inactive controls (bit map) */
 
+	/* autogain and exposure or gain control cluster, these are global as
+	   the autogain/exposure functions in autogain_functions.c use them */
+	struct {
+		struct v4l2_ctrl *autogain;
+		struct v4l2_ctrl *exposure;
+		struct v4l2_ctrl *gain;
+		int exp_too_low_cnt, exp_too_high_cnt;
+	};
+
 #define USB_BUF_SZ 64
 	__u8 *usb_buf;				/* buffer for USB exchanges */
 	struct urb *urb[MAX_NURBS];
@@ -242,4 +252,9 @@ int gspca_resume(struct usb_interface *intf);
 #endif
 int gspca_auto_gain_n_exposure(struct gspca_dev *gspca_dev, int avg_lum,
 	int desired_avg_lum, int deadzone, int gain_knee, int exposure_knee);
+int gspca_expo_autogain(struct gspca_dev *gspca_dev, int avg_lum,
+	int desired_avg_lum, int deadzone, int gain_knee, int exposure_knee);
+int gspca_coarse_grained_expo_autogain(struct gspca_dev *gspca_dev,
+        int avg_lum, int desired_avg_lum, int deadzone);
+
 #endif /* GSPCAV2_H */