V4L/DVB (13009): gspca - stv06xx-hdcs: Reduce exposure range

Due to rounding and clipping, exposure and gain settings do not map to
unique register values.  Rather than read the registers and report gain
and exposure that may be different than the values that were set, just
cache the latest values that were set and report them.  Reduce exposure
range from 0-65535 to 0-255 so libv4l's autogain doesn't take forever.
Remove vestiges of driver signal processing that is now handled by
libv4l.
Signed-off-by: James Blanford <jhblanford@gmail.com>
Signed-off-by: Erik Andrén <erik.andren@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/stv06xx/stv06xx_hdcs.c

@@ -37,7 +37,7 @@ static const struct ctrl hdcs1x00_ctrl[] = {
 			.type		= V4L2_CTRL_TYPE_INTEGER,
 			.name		= "exposure",
 			.minimum	= 0x00,
-			.maximum	= 0xffff,
+			.maximum	= 0xff,
 			.step		= 0x1,
 			.default_value 	= HDCS_DEFAULT_EXPOSURE,
 			.flags         	= V4L2_CTRL_FLAG_SLIDER
@@ -148,6 +148,7 @@ struct hdcs {
 	} exp;
 
 	int psmp;
+	u8 exp_cache, gain_cache;
 };
 
 static int hdcs_reg_write_seq(struct sd *sd, u8 reg, u8 *vals, u8 len)
@@ -233,34 +234,8 @@ static int hdcs_get_exposure(struct gspca_dev *gspca_dev, __s32 *val)
 	struct sd *sd = (struct sd *) gspca_dev;
 	struct hdcs *hdcs = sd->sensor_priv;
 
-	/* Column time period */
-	int ct;
-	/* Column processing period */
-	int cp;
-	/* Row processing period */
-	int rp;
-	int cycles;
-	int err;
-	int rowexp;
-	u16 data[2];
-
-	err = stv06xx_read_sensor(sd, HDCS_ROWEXPL, &data[0]);
-	if (err < 0)
-		return err;
-
-	err = stv06xx_read_sensor(sd, HDCS_ROWEXPH, &data[1]);
-	if (err < 0)
-		return err;
-
-	rowexp = (data[1] << 8) | data[0];
+	*val = hdcs->exp_cache;
 
-	ct = hdcs->exp.cto + hdcs->psmp + (HDCS_ADC_START_SIG_DUR + 2);
-	cp = hdcs->exp.cto + (hdcs->w * ct / 2);
-	rp = hdcs->exp.rs + cp;
-
-	cycles = rp * rowexp;
-	*val = cycles / HDCS_CLK_FREQ_MHZ;
-	PDEBUG(D_V4L2, "Read exposure %d", *val);
 	return 0;
 }
 
@@ -282,7 +257,10 @@ static int hdcs_set_exposure(struct gspca_dev *gspca_dev, __s32 val)
 	int cycles, err;
 	u8 exp[14];
 
-	cycles = val * HDCS_CLK_FREQ_MHZ;
+	val &= 0xff;
+	hdcs->exp_cache = val;
+
+	cycles = val * HDCS_CLK_FREQ_MHZ * 257;
 
 	ct = hdcs->exp.cto + hdcs->psmp + (HDCS_ADC_START_SIG_DUR + 2);
 	cp = hdcs->exp.cto + (hdcs->w * ct / 2);
@@ -353,49 +331,42 @@ static int hdcs_set_exposure(struct gspca_dev *gspca_dev, __s32 val)
 	return err;
 }
 
-static int hdcs_set_gains(struct sd *sd, u8 r, u8 g, u8 b)
+static int hdcs_set_gains(struct sd *sd, u8 g)
 {
+	struct hdcs *hdcs = sd->sensor_priv;
+	int err;
 	u8 gains[4];
 
+	hdcs->gain_cache = g;
+
 	/* the voltage gain Av = (1 + 19 * val / 127) * (1 + bit7) */
-	if (r > 127)
-		r = 0x80 | (r / 2);
 	if (g > 127)
 		g = 0x80 | (g / 2);
-	if (b > 127)
-		b = 0x80 | (b / 2);
 
 	gains[0] = g;
-	gains[1] = r;
-	gains[2] = b;
+	gains[1] = g;
+	gains[2] = g;
 	gains[3] = g;
 
-	return hdcs_reg_write_seq(sd, HDCS_ERECPGA, gains, 4);
+	err = hdcs_reg_write_seq(sd, HDCS_ERECPGA, gains, 4);
+		return err;
 }
 
 static int hdcs_get_gain(struct gspca_dev *gspca_dev, __s32 *val)
 {
 	struct sd *sd = (struct sd *) gspca_dev;
-	int err;
-	u16 data;
+	struct hdcs *hdcs = sd->sensor_priv;
 
-	err = stv06xx_read_sensor(sd, HDCS_ERECPGA, &data);
+	*val = hdcs->gain_cache;
 
-	/* Bit 7 doubles the gain */
-	if (data & 0x80)
-		*val = (data & 0x7f) * 2;
-	else
-		*val = data;
-
-	PDEBUG(D_V4L2, "Read gain %d", *val);
-	return err;
+	return 0;
 }
 
 static int hdcs_set_gain(struct gspca_dev *gspca_dev, __s32 val)
 {
 	PDEBUG(D_V4L2, "Writing gain %d", val);
 	return hdcs_set_gains((struct sd *) gspca_dev,
-			       val & 0xff, val & 0xff, val & 0xff);
+			       val & 0xff);
 }
 
 static int hdcs_set_size(struct sd *sd,
@@ -613,8 +584,7 @@ static int hdcs_init(struct sd *sd)
 	if (err < 0)
 		return err;
 
-	err = hdcs_set_gains(sd, HDCS_DEFAULT_GAIN, HDCS_DEFAULT_GAIN,
-			     HDCS_DEFAULT_GAIN);
+	err = hdcs_set_gains(sd, HDCS_DEFAULT_GAIN);
 	if (err < 0)
 		return err;
 

drivers/media/video/gspca/stv06xx/stv06xx_hdcs.h

@@ -124,7 +124,7 @@
 #define HDCS_RUN_ENABLE		(1 << 2)
 #define HDCS_SLEEP_MODE		(1 << 1)
 
-#define HDCS_DEFAULT_EXPOSURE	5000
+#define HDCS_DEFAULT_EXPOSURE	48
 #define HDCS_DEFAULT_GAIN	128
 
 static int hdcs_probe_1x00(struct sd *sd);