V4L/DVB (13895): gspca - zc3xx: Fix the contrast control.

The previous calculation gave bad gamma tables.
Signed-off-by: NJean-Francois Moine <moinejf@free.fr>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/zc3xx.c

@@ -115,7 +115,7 @@ static struct ctrl sd_ctrls[] = {
 		.type    = V4L2_CTRL_TYPE_INTEGER,
 		.name    = "Contrast",
 		.minimum = 0,
-		.maximum = 256,
+		.maximum = 255,
 		.step    = 1,
 		.default_value = 128,
 	    },
@@ -6053,105 +6053,55 @@ static void setcontrast(struct gspca_dev *gspca_dev)
 {
 	struct sd *sd = (struct sd *) gspca_dev;
 	struct usb_device *dev = gspca_dev->dev;
-	const __u8 *Tgamma, *Tgradient;
-	int g, i, k;
-	static const __u8 kgamma_tb[16] =	/* delta for contrast */
+	const __u8 *Tgamma;
+	int g, i, k, adj, gp;
+	u8 gr[16];
+	static const u8 delta_tb[16] =		/* delta for contrast */
 		{0x15, 0x0d, 0x0a, 0x09, 0x08, 0x08, 0x08, 0x08,
 		 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08};
-	static const __u8 kgrad_tb[16] =
-		{0x1b, 0x06, 0x03, 0x02, 0x00, 0x00, 0x00, 0x00,
-		 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x06, 0x04};
-	static const __u8 Tgamma_1[16] =
+	static const u8 gamma_tb[6][16] = {
 		{0x00, 0x00, 0x03, 0x0d, 0x1b, 0x2e, 0x45, 0x5f,
-		 0x79, 0x93, 0xab, 0xc1, 0xd4, 0xe5, 0xf3, 0xff};
-	static const __u8 Tgradient_1[16] =
-		{0x00, 0x01, 0x05, 0x0b, 0x10, 0x15, 0x18, 0x1a,
-		 0x1a, 0x18, 0x16, 0x14, 0x12, 0x0f, 0x0d, 0x06};
-	static const __u8 Tgamma_2[16] =
+		 0x79, 0x93, 0xab, 0xc1, 0xd4, 0xe5, 0xf3, 0xff},
 		{0x01, 0x0c, 0x1f, 0x3a, 0x53, 0x6d, 0x85, 0x9c,
-		 0xb0, 0xc2, 0xd1, 0xde, 0xe9, 0xf2, 0xf9, 0xff};
-	static const __u8 Tgradient_2[16] =
-		{0x05, 0x0f, 0x16, 0x1a, 0x19, 0x19, 0x17, 0x15,
-		 0x12, 0x10, 0x0e, 0x0b, 0x09, 0x08, 0x06, 0x03};
-	static const __u8 Tgamma_3[16] =
+		 0xb0, 0xc2, 0xd1, 0xde, 0xe9, 0xf2, 0xf9, 0xff},
 		{0x04, 0x16, 0x30, 0x4e, 0x68, 0x81, 0x98, 0xac,
-		 0xbe, 0xcd, 0xda, 0xe4, 0xed, 0xf5, 0xfb, 0xff};
-	static const __u8 Tgradient_3[16] =
-		{0x0c, 0x16, 0x1b, 0x1c, 0x19, 0x18, 0x15, 0x12,
-		 0x10, 0x0d, 0x0b, 0x09, 0x08, 0x06, 0x05, 0x03};
-	static const __u8 Tgamma_4[16] =
+		 0xbe, 0xcd, 0xda, 0xe4, 0xed, 0xf5, 0xfb, 0xff},
 		{0x13, 0x38, 0x59, 0x79, 0x92, 0xa7, 0xb9, 0xc8,
-		 0xd4, 0xdf, 0xe7, 0xee, 0xf4, 0xf9, 0xfc, 0xff};
-	static const __u8 Tgradient_4[16] =
-		{0x26, 0x22, 0x20, 0x1c, 0x16, 0x13, 0x10, 0x0d,
-		 0x0b, 0x09, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02};
-	static const __u8 Tgamma_5[16] =
+		 0xd4, 0xdf, 0xe7, 0xee, 0xf4, 0xf9, 0xfc, 0xff},
 		{0x20, 0x4b, 0x6e, 0x8d, 0xa3, 0xb5, 0xc5, 0xd2,
-		 0xdc, 0xe5, 0xec, 0xf2, 0xf6, 0xfa, 0xfd, 0xff};
-	static const __u8 Tgradient_5[16] =
-		{0x37, 0x26, 0x20, 0x1a, 0x14, 0x10, 0x0e, 0x0b,
-		 0x09, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x02};
-	static const __u8 Tgamma_6[16] =		/* ?? was gamma 5 */
+		 0xdc, 0xe5, 0xec, 0xf2, 0xf6, 0xfa, 0xfd, 0xff},
 		{0x24, 0x44, 0x64, 0x84, 0x9d, 0xb2, 0xc4, 0xd3,
-		 0xe0, 0xeb, 0xf4, 0xff, 0xff, 0xff, 0xff, 0xff};
-	static const __u8 Tgradient_6[16] =
-		{0x18, 0x20, 0x20, 0x1c, 0x16, 0x13, 0x10, 0x0e,
-		 0x0b, 0x09, 0x07, 0x00, 0x00, 0x00, 0x00, 0x01};
-	static const __u8 *gamma_tb[] = {
-		NULL, Tgamma_1, Tgamma_2,
-		Tgamma_3, Tgamma_4, Tgamma_5, Tgamma_6
-	};
-	static const __u8 *gradient_tb[] = {
-		NULL, Tgradient_1, Tgradient_2,
-		Tgradient_3, Tgradient_4, Tgradient_5, Tgradient_6
+		 0xe0, 0xeb, 0xf4, 0xff, 0xff, 0xff, 0xff, 0xff},
 	};
-#ifdef GSPCA_DEBUG
-	__u8 v[16];
-#endif
 
-	Tgamma = gamma_tb[sd->gamma];
-	Tgradient = gradient_tb[sd->gamma];
+	Tgamma = gamma_tb[sd->gamma - 1];
 
-	k = (sd->contrast - 128)		/* -128 / 128 */
-			* Tgamma[0];
-	PDEBUG(D_CONF, "gamma:%d contrast:%d gamma coeff: %d/128",
-		sd->gamma, sd->contrast, k);
+	k = ((int) sd->contrast - 128);		/* -128 / 128 */
+	adj = 0;
+	gp = 0;
 	for (i = 0; i < 16; i++) {
-		g = Tgamma[i] + kgamma_tb[i] * k / 128;
+		g = Tgamma[i] - delta_tb[i] * k / 128 - adj / 2;
 		if (g > 0xff)
 			g = 0xff;
 		else if (g <= 0)
 			g = 1;
 		reg_w(dev, g, 0x0120 + i);	/* gamma */
-#ifdef GSPCA_DEBUG
-		if (gspca_debug & D_CONF)
-			v[i] = g;
-#endif
-	}
-	PDEBUG(D_CONF, "tb: %02x %02x %02x %02x %02x %02x %02x %02x",
-		v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7]);
-	PDEBUG(D_CONF, "    %02x %02x %02x %02x %02x %02x %02x %02x",
-		v[8], v[9], v[10], v[11], v[12], v[13], v[14], v[15]);
-	for (i = 0; i < 16; i++) {
-		g = Tgradient[i] - kgrad_tb[i] * k / 128;
-		if (g > 0xff)
-			g = 0xff;
-		else if (g <= 0) {
-			if (i != 15)
-				g = 0;
+		if (k > 0)
+			adj--;
+		else
+			adj++;
+
+		if (i != 0) {
+			if (gp == 0)
+				gr[i - 1] = 0;
 			else
-				g = 1;
+				gr[i - 1] = g - gp;
 		}
-		reg_w(dev, g, 0x0130 + i);	/* gradient */
-#ifdef GSPCA_DEBUG
-		if (gspca_debug & D_CONF)
-			v[i] = g;
-#endif
+		gp = g;
 	}
-	PDEBUG(D_CONF, "    %02x %02x %02x %02x %02x %02x %02x %02x",
-		v[0], v[1], v[2], v[3], v[4], v[5], v[6], v[7]);
-	PDEBUG(D_CONF, "    %02x %02x %02x %02x %02x %02x %02x %02x",
-		v[8], v[9], v[10], v[11], v[12], v[13], v[14], v[15]);
+	gr[15] = gr[14] / 2;
+	for (i = 0; i < 16; i++)
+		reg_w(dev, gr[i], 0x0130 + i);	/* gradient */
 }
 
 static void setquality(struct gspca_dev *gspca_dev)