Currently used registers 0xc5 and 0xc7 provide only a very coarse
adjustment possibility within a very small value range (0-3).
With registers 0x01 and 0x03, a fine grained adjustment with
255 steps is possible. This is also what the Windows driver does.
Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
---
drivers/media/usb/gspca/pac7302.c | 51 +++++++++++++++++++++++++++++--------
1 files changed, 40 insertions(+), 11 deletions(-)
diff --git a/drivers/media/usb/gspca/pac7302.c b/drivers/media/usb/gspca/pac7302.c
index 4894ac1..8a0f4d6 100644
--- a/drivers/media/usb/gspca/pac7302.c
+++ b/drivers/media/usb/gspca/pac7302.c
@@ -77,12 +77,12 @@
*
* Page | Register | Function
* -----+------------+---------------------------------------------------
+ * 0 | 0x01 | setredbalance()
+ * 0 | 0x03 | setbluebalance()
* 0 | 0x0f..0x20 | setcolors()
* 0 | 0xa2..0xab | setbrightcont()
* 0 | 0xb6 | setsharpness()
- * 0 | 0xc5 | setredbalance()
* 0 | 0xc6 | setwhitebalance()
- * 0 | 0xc7 | setbluebalance()
* 0 | 0xdc | setbrightcont(), setcolors()
* 3 | 0x02 | setexposure()
* 3 | 0x10, 0x12 | setgain()
@@ -98,10 +98,13 @@
/* Include pac common sof detection functions */
#include "pac_common.h"
-#define PAC7302_GAIN_DEFAULT 15
-#define PAC7302_GAIN_KNEE 42
-#define PAC7302_EXPOSURE_DEFAULT 66 /* 33 ms / 30 fps */
-#define PAC7302_EXPOSURE_KNEE 133 /* 66 ms / 15 fps */
+#define PAC7302_RGB_BALANCE_MIN 0
+#define PAC7302_RGB_BALANCE_MAX 200
+#define PAC7302_RGB_BALANCE_DEFAULT 100
+#define PAC7302_GAIN_DEFAULT 15
+#define PAC7302_GAIN_KNEE 42
+#define PAC7302_EXPOSURE_DEFAULT 66 /* 33 ms / 30 fps */
+#define PAC7302_EXPOSURE_KNEE 133 /* 66 ms / 15 fps */
MODULE_AUTHOR("Jean-Francois Moine <http://moinejf.free.fr>, "
"Thomas Kaiser thomas@xxxxxxxxxxxxxxx");
@@ -438,12 +441,31 @@ static void setwhitebalance(struct gspca_dev *gspca_dev)
reg_w(gspca_dev, 0xdc, 0x01);
}
+static u8 rgbbalance_ctrl_to_reg_value(s32 rgb_ctrl_val)
+{
+ const unsigned int k = 1000; /* precision factor */
+ unsigned int norm;
+
+ /* Normed value [0...k] */
+ norm = k * (rgb_ctrl_val - PAC7302_RGB_BALANCE_MIN)
+ / (PAC7302_RGB_BALANCE_MAX - PAC7302_RGB_BALANCE_MIN);
+ /* Qudratic apporach improves control at small (register) values: */
+ return 64 * norm * norm / (k*k) + 32 * norm / k + 32;
+ /* Y = 64*X*X + 32*X + 32
+ * => register values 0x20-0x80; Windows driver uses these limits */
+
+ /* NOTE: for full value range (0x00-0xff) use
+ * Y = 254*X*X + X
+ * => 254 * norm * norm / (k*k) + 1 * norm / k */
+}
+
static void setredbalance(struct gspca_dev *gspca_dev)
{
struct sd *sd = (struct sd *) gspca_dev;
- reg_w(gspca_dev, 0xff, 0x00); /* page 0 */
- reg_w(gspca_dev, 0xc5, sd->red_balance->val);
+ reg_w(gspca_dev, 0xff, 0x00); /* page 0 */
+ reg_w(gspca_dev, 0x01,
+ rgbbalance_ctrl_to_reg_value(sd->red_balance->val));
reg_w(gspca_dev, 0xdc, 0x01);
}
@@ -453,7 +475,8 @@ static void setbluebalance(struct gspca_dev *gspca_dev)
struct sd *sd = (struct sd *) gspca_dev;
reg_w(gspca_dev, 0xff, 0x00); /* page 0 */
- reg_w(gspca_dev, 0xc7, sd->blue_balance->val);
+ reg_w(gspca_dev, 0x03,
+ rgbbalance_ctrl_to_reg_value(sd->blue_balance->val));
reg_w(gspca_dev, 0xdc, 0x01);
}
@@ -642,9 +665,15 @@ static int sd_init_controls(struct gspca_dev *gspca_dev)
V4L2_CID_WHITE_BALANCE_TEMPERATURE,
0, 255, 1, 55);
sd->red_balance = v4l2_ctrl_new_std(hdl, &sd_ctrl_ops,
- V4L2_CID_RED_BALANCE, 0, 3, 1, 1);
+ V4L2_CID_RED_BALANCE,
+ PAC7302_RGB_BALANCE_MIN,
+ PAC7302_RGB_BALANCE_MAX,
+ 1, PAC7302_RGB_BALANCE_DEFAULT);
sd->blue_balance = v4l2_ctrl_new_std(hdl, &sd_ctrl_ops,
- V4L2_CID_BLUE_BALANCE, 0, 3, 1, 1);
+ V4L2_CID_BLUE_BALANCE,
+ PAC7302_RGB_BALANCE_MIN,
+ PAC7302_RGB_BALANCE_MAX,
+ 1, PAC7302_RGB_BALANCE_DEFAULT);
gspca_dev->autogain = v4l2_ctrl_new_std(hdl, &sd_ctrl_ops,
V4L2_CID_AUTOGAIN, 0, 1, 1, 1);
--
1.7.7
--
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