V4L/DVB (8357): gspca: Perfect exposure for sn9c10x, sensor ov6650.
Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/gspca/sonixb.c b/drivers/media/video/gspca/sonixb.c
index c0ce21f..7303df0 100644
--- a/drivers/media/video/gspca/sonixb.c
+++ b/drivers/media/video/gspca/sonixb.c
@@ -121,8 +121,8 @@
.id = V4L2_CID_EXPOSURE,
.type = V4L2_CTRL_TYPE_INTEGER,
.name = "Exposure",
-#define EXPOSURE_DEF 0
-#define EXPOSURE_KNEE 176 /* 10 fps */
+#define EXPOSURE_DEF 16 /* 32 ms / 30 fps */
+#define EXPOSURE_KNEE 50 /* 100 ms / 10 fps */
.minimum = 0,
.maximum = 255,
.step = 1,
@@ -611,8 +611,6 @@
static void setexposure(struct gspca_dev *gspca_dev)
{
struct sd *sd = (struct sd *) gspca_dev;
- /* translate 0 - 255 to a number of fps in a 30 - 1 scale */
- int fps = 30 - sd->exposure * 29 / 255;
switch (sd->sensor) {
case SENSOR_TAS5110: {
@@ -621,19 +619,53 @@
/* 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 = 60 / fps;
- if (reg > 15)
+ reg = 120 * sd->exposure / 1000;
+ if (reg < 2)
+ reg = 2;
+ else if (reg > 15)
reg = 15;
reg = (reg << 4) | 0x0b;
reg_w(gspca_dev, 0x19, ®, 1);
break;
}
case SENSOR_OV6650: {
- __u8 i2c[] = {0xa0, 0x60, 0x11, 0xc0, 0x00, 0x00, 0x00, 0x10};
- i2c[3] = 30 / fps - 1;
- if (i2c[3] > 15)
- i2c[3] = 15;
- i2c[3] |= 0xc0;
+ /* The ov6650 has 2 registers which both influence exposure,
+ first there is register 11, whose low nibble sets the no fps
+ according to: fps = 30 / (low_nibble + 1)
+
+ The fps configures the maximum exposure setting, but it is
+ possible to use less exposure then what the fps maximum
+ allows by setting register 10. register 10 configures the
+ actual exposure as quotient of the full exposure, with 0
+ being no exposure at all (not very usefull) and reg10_max
+ being max exposure possible at that framerate.
+
+ The code maps our 0 - 510 ms exposure ctrl to these 2
+ registers, trying to keep fps as high as possible.
+ */
+ __u8 i2c[] = {0xb0, 0x60, 0x10, 0x00, 0xc0, 0x00, 0x00, 0x10};
+ int reg10, reg11;
+ /* No clear idea why, but setting reg10 above this value
+ results in no change */
+ const int reg10_max = 0x4d;
+
+ reg11 = (60 * sd->exposure + 999) / 1000;
+ if (reg11 < 1)
+ reg11 = 1;
+ else if (reg11 > 16)
+ reg11 = 16;
+
+ /* 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);
+ if (reg10 < 1) /* 0 is a valid value, but is very _black_ */
+ reg10 = 1;
+ else if (reg10 > reg10_max)
+ reg10 = reg10_max;
+
+ /* Write reg 10 and reg11 low nibble */
+ i2c[3] = reg10;
+ i2c[4] |= reg11 - 1;
if (i2c_w(gspca_dev, i2c) < 0)
PDEBUG(D_ERR, "i2c error exposure");
break;