V4L/DVB: gscpa_sonixb: Differentiate between sensors with a coarse and fine expo ctrl

Some sensors only allow controlling the exposure by changing the clockdiv,
which means that exposure takes pretty large jumps (for example when going
from a div of 1 to 2, the exposure doubles). Use 2 different entries in
the controls array for these 2 different types of exposure (always
disabling one), and;

Add a new autogain algorithm for the coarse exposure case, which normally
changes the gain setting, only touching the exposure setting if the desired
luminance cannot be reached with gain, and after an exposure change once more
first tries gain, etc. Thus avoiding exposure changes, and the resulting
oscilation because of the huge steps these exposure controls take.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/coarse_expo_autogain.h

+/*
+ * 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;
+}

drivers/media/video/gspca/gspca.c

@@ -2417,6 +2417,8 @@ int gspca_auto_gain_n_exposure(struct gspca_dev *gspca_dev, int avg_lum,
 	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)

drivers/media/video/gspca/sonixb.c

@@ -54,9 +54,11 @@ struct sd {
 	struct gspca_dev gspca_dev;	/* !! must be the first item */
 	atomic_t avg_lum;
 	int prev_avg_lum;
+	int exp_too_low_cnt;
+	int exp_too_high_cnt;
 
+	unsigned short exposure;
 	unsigned char gain;
-	unsigned char exposure;
 	unsigned char brightness;
 	unsigned char autogain;
 	unsigned char autogain_ignore_frames;
@@ -97,13 +99,15 @@ struct sensor_data {
 /* sensor_data flags */
 #define F_GAIN 0x01		/* has gain */
 #define F_SIF  0x02		/* sif or vga */
+#define F_COARSE_EXPO 0x04	/* exposure control is coarse */
 
 /* priv field of struct v4l2_pix_format flags (do not use low nibble!) */
 #define MODE_RAW 0x10		/* raw bayer mode */
 #define MODE_REDUCED_SIF 0x20	/* vga mode (320x240 / 160x120) on sif cam */
 
 /* ctrl_dis helper macros */
-#define NO_EXPO ((1 << EXPOSURE_IDX) | (1 << AUTOGAIN_IDX))
+#define NO_EXPO ((1 << EXPOSURE_IDX) | (1 << COARSE_EXPOSURE_IDX) | \
+		 (1 << AUTOGAIN_IDX))
 #define NO_FREQ (1 << FREQ_IDX)
 #define NO_BRIGHTNESS (1 << BRIGHTNESS_IDX)
 
@@ -129,11 +133,10 @@ struct sensor_data {
 }
 
 /* We calculate the autogain at the end of the transfer of a frame, at this
-   moment a frame with the old settings is being transmitted, and a frame is
-   being captured with the old settings. So if we adjust the autogain we must
-   ignore atleast the 2 next frames for the new settings to come into effect
-   before doing any other adjustments */
-#define AUTOGAIN_IGNORE_FRAMES 3
+   moment a frame with the old settings is being captured and transmitted. So
+   if we adjust the gain or exposure we must ignore atleast the next frame for
+   the new settings to come into effect before doing any other adjustments. */
+#define AUTOGAIN_IGNORE_FRAMES 1
 
 /* V4L2 controls supported by the driver */
 static int sd_setbrightness(struct gspca_dev *gspca_dev, __s32 val);
@@ -185,10 +188,10 @@ static const struct ctrl sd_ctrls[] = {
 			.id = V4L2_CID_EXPOSURE,
 			.type = V4L2_CTRL_TYPE_INTEGER,
 			.name = "Exposure",
-#define EXPOSURE_DEF  16 /*  32 ms / 30 fps */
-#define EXPOSURE_KNEE 50 /* 100 ms / 10 fps */
+#define EXPOSURE_DEF  33 /*  33 ms / 30 fps */
+#define EXPOSURE_KNEE 100 /* 100 ms / 10 fps */
 			.minimum = 0,
-			.maximum = 255,
+			.maximum = 511,
 			.step = 1,
 			.default_value = EXPOSURE_DEF,
 			.flags = 0,
@@ -196,7 +199,23 @@ static const struct ctrl sd_ctrls[] = {
 		.set = sd_setexposure,
 		.get = sd_getexposure,
 	},
-#define AUTOGAIN_IDX 3
+#define COARSE_EXPOSURE_IDX 3
+	{
+		{
+			.id = V4L2_CID_EXPOSURE,
+			.type = V4L2_CTRL_TYPE_INTEGER,
+			.name = "Exposure",
+#define COARSE_EXPOSURE_DEF  2 /* 30 fps */
+			.minimum = 2,
+			.maximum = 15,
+			.step = 1,
+			.default_value = COARSE_EXPOSURE_DEF,
+			.flags = 0,
+		},
+		.set = sd_setexposure,
+		.get = sd_getexposure,
+	},
+#define AUTOGAIN_IDX 4
 	{
 		{
 			.id = V4L2_CID_AUTOGAIN,
@@ -212,7 +231,7 @@ static const struct ctrl sd_ctrls[] = {
 		.set = sd_setautogain,
 		.get = sd_getautogain,
 	},
-#define FREQ_IDX 4
+#define FREQ_IDX 5
 	{
 		{
 			.id	 = V4L2_CID_POWER_LINE_FREQUENCY,
@@ -507,10 +526,10 @@ SENS(initPas106, NULL, pas106_sensor_init, NULL, NULL, F_SIF, NO_EXPO|NO_FREQ,
 	0),
 SENS(initPas202, initPas202, pas202_sensor_init, NULL, NULL, 0,
 	NO_EXPO|NO_FREQ, 0),
-SENS(initTas5110c, NULL, tas5110_sensor_init, NULL, NULL, F_GAIN|F_SIF,
-	NO_BRIGHTNESS|NO_FREQ, 0),
-SENS(initTas5110d, NULL, tas5110_sensor_init, NULL, NULL, F_GAIN|F_SIF,
-	NO_BRIGHTNESS|NO_FREQ, 0),
+SENS(initTas5110c, NULL, tas5110_sensor_init, NULL, NULL,
+	F_GAIN|F_SIF|F_COARSE_EXPO, NO_BRIGHTNESS|NO_FREQ, 0),
+SENS(initTas5110d, NULL, tas5110_sensor_init, NULL, NULL,
+	F_GAIN|F_SIF|F_COARSE_EXPO, NO_BRIGHTNESS|NO_FREQ, 0),
 SENS(initTas5130, NULL, tas5130_sensor_init, NULL, NULL, 0, NO_EXPO|NO_FREQ,
 	0),
 };
@@ -721,16 +740,10 @@ static void setexposure(struct gspca_dev *gspca_dev)
 	switch (sd->sensor) {
 	case SENSOR_TAS5110C:
 	case SENSOR_TAS5110D: {
-		__u8 reg;
-
 		/* register 19's high nibble contains the sn9c10x clock divider
 		   The high nibble configures the no fps according to the
 		   formula: 60 / high_nibble. With a maximum of 30 fps */
-		reg = 120 * sd->exposure / 1000;
-		if (reg < 2)
-			reg = 2;
-		else if (reg > 15)
-			reg = 15;
+		__u8 reg = sd->exposure;
 		reg = (reg << 4) | 0x0b;
 		reg_w(gspca_dev, 0x19, &reg, 1);
 		break;
@@ -766,7 +779,7 @@ static void setexposure(struct gspca_dev *gspca_dev)
 		} else
 			reg10_max = 0x41;
 
-		reg11 = (60 * sd->exposure + 999) / 1000;
+		reg11 = (30 * sd->exposure + 999) / 1000;
 		if (reg11 < 1)
 			reg11 = 1;
 		else if (reg11 > 16)
@@ -778,8 +791,8 @@ static void setexposure(struct gspca_dev *gspca_dev)
 			reg11 = 3;
 
 		/* frame exposure time in ms = 1000 * reg11 / 30    ->
-		reg10 = sd->exposure * 2 * reg10_max / (1000 * reg11 / 30) */
-		reg10 = (sd->exposure * 60 * reg10_max) / (1000 * reg11);
+		reg10 = sd->exposure * reg10_max / (1000 * reg11 / 30) */
+		reg10 = (sd->exposure * 30 * reg10_max) / (1000 * reg11);
 
 		/* Don't allow this to get below 10 when using autogain, the
 		   steps become very large (relatively) when below 10 causing
@@ -839,30 +852,43 @@ static void setfreq(struct gspca_dev *gspca_dev)
 	}
 }
 
+#include "coarse_expo_autogain.h"
+
 static void do_autogain(struct gspca_dev *gspca_dev)
 {
-	int deadzone, desired_avg_lum;
+	int deadzone, desired_avg_lum, result;
 	struct sd *sd = (struct sd *) gspca_dev;
 	int avg_lum = atomic_read(&sd->avg_lum);
 
-	if (avg_lum == -1)
+	if (avg_lum == -1 || !sd->autogain)
+		return;
+
+	if (sd->autogain_ignore_frames > 0) {
+		sd->autogain_ignore_frames--;
 		return;
+	}
 
 	/* SIF / VGA sensors have a different autoexposure area and thus
 	   different avg_lum values for the same picture brightness */
 	if (sensor_data[sd->sensor].flags & F_SIF) {
-		deadzone = 1000;
-		desired_avg_lum = 7000;
+		deadzone = 500;
+		/* SIF sensors tend to overexpose, so keep this small */
+		desired_avg_lum = 5000;
 	} else {
-		deadzone = 3000;
+		deadzone = 1500;
 		desired_avg_lum = 23000;
 	}
 
-	if (sd->autogain_ignore_frames > 0)
-		sd->autogain_ignore_frames--;
-	else if (gspca_auto_gain_n_exposure(gspca_dev, avg_lum,
-			sd->brightness * desired_avg_lum / 127,
-			deadzone, GAIN_KNEE, EXPOSURE_KNEE)) {
+	if (sensor_data[sd->sensor].flags & F_COARSE_EXPO)
+		result = gspca_coarse_grained_expo_autogain(gspca_dev, avg_lum,
+				sd->brightness * desired_avg_lum / 127,
+				deadzone);
+	else
+		result = gspca_auto_gain_n_exposure(gspca_dev, avg_lum,
+				sd->brightness * desired_avg_lum / 127,
+				deadzone, GAIN_KNEE, EXPOSURE_KNEE);
+
+	if (result) {
 		PDEBUG(D_FRAM, "autogain: gain changed: gain: %d expo: %d",
 			(int)sd->gain, (int)sd->exposure);
 		sd->autogain_ignore_frames = AUTOGAIN_IGNORE_FRAMES;
@@ -897,7 +923,13 @@ static int sd_config(struct gspca_dev *gspca_dev,
 
 	sd->brightness = BRIGHTNESS_DEF;
 	sd->gain = GAIN_DEF;
-	sd->exposure = EXPOSURE_DEF;
+	if (sensor_data[sd->sensor].flags & F_COARSE_EXPO) {
+		sd->exposure = COARSE_EXPOSURE_DEF;
+		gspca_dev->ctrl_dis |= (1 << EXPOSURE_IDX);
+	} else {
+		sd->exposure = EXPOSURE_DEF;
+		gspca_dev->ctrl_dis |= (1 << COARSE_EXPOSURE_IDX);
+	}
 	if (gspca_dev->ctrl_dis & (1 << AUTOGAIN_IDX))
 		sd->autogain = 0; /* Disable do_autogain callback */
 	else
@@ -1001,6 +1033,8 @@ static int sd_start(struct gspca_dev *gspca_dev)
 
 	sd->frames_to_drop = 0;
 	sd->autogain_ignore_frames = 0;
+	sd->exp_too_high_cnt = 0;
+	sd->exp_too_low_cnt = 0;
 	atomic_set(&sd->avg_lum, -1);
 	return 0;
 }
@@ -1159,11 +1193,14 @@ static int sd_setautogain(struct gspca_dev *gspca_dev, __s32 val)
 	struct sd *sd = (struct sd *) gspca_dev;
 
 	sd->autogain = val;
+	sd->exp_too_high_cnt = 0;
+	sd->exp_too_low_cnt = 0;
+
 	/* when switching to autogain set defaults to make sure
 	   we are on a valid point of the autogain gain /
 	   exposure knee graph, and give this change time to
 	   take effect before doing autogain. */
-	if (sd->autogain) {
+	if (sd->autogain && !(sensor_data[sd->sensor].flags & F_COARSE_EXPO)) {
 		sd->exposure = EXPOSURE_DEF;
 		sd->gain = GAIN_DEF;
 		if (gspca_dev->streaming) {