V4L/DVB (8348): gspca: Add auto gain/exposure to sonixb and tas5110 / ov6650 sensors.

sonixb:   Do auto gain for tas5110 / ov6650 sensors.
pac207:   Move the auto_gain function to gspca.
gspca:    New function gspca_auto_gain_n_exposure().

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>

1 files changed, 88 insertions, 0 deletions

diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index 09f190c689d5..2ffb00ab0811 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -1790,6 +1790,94 @@ void gspca_disconnect(struct usb_interface *intf)
 }
 EXPORT_SYMBOL(gspca_disconnect);
 
+/* -- cam driver utility functions -- */
+
+/* auto gain and exposure algorithm based on the knee algorithm described here:
+   http://ytse.tricolour.net/docs/LowLightOptimization.html
+
+   Returns 0 if no changes were made, 1 if the gain and or exposure settings
+   where changed. */
+int gspca_auto_gain_n_exposure(struct gspca_dev *gspca_dev, int avg_lum,
+        int desired_avg_lum, int deadzone, int gain_knee, int exposure_knee)
+{
+        int i, steps, gain, orig_gain, exposure, orig_exposure, autogain;
+        const struct ctrl *gain_ctrl = NULL;
+        const struct ctrl *exposure_ctrl = NULL;
+        const struct ctrl *autogain_ctrl = NULL;
+        int retval = 0;
+
+        for (i = 0; i < gspca_dev->sd_desc->nctrls; i++) {
+                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 (gspca_dev->sd_desc->ctrls[i].qctrl.id == V4L2_CID_AUTOGAIN)
+                        autogain_ctrl = &gspca_dev->sd_desc->ctrls[i];
+        }
+        if (!gain_ctrl || !exposure_ctrl || !autogain_ctrl) {
+                PDEBUG(D_ERR, "Error: gspca_auto_gain_n_exposure called "
+                        "on cam without (auto)gain/exposure");
+                return 0;
+        }
+
+        if (gain_ctrl->get(gspca_dev, &gain) ||
+                        exposure_ctrl->get(gspca_dev, &exposure) ||
+                        autogain_ctrl->get(gspca_dev, &autogain) || !autogain)
+                return 0;
+
+        orig_gain = gain;
+        orig_exposure = exposure;
+
+        /* 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 = abs(desired_avg_lum - avg_lum) / deadzone;
+
+        PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d\n",
+                avg_lum, desired_avg_lum, steps);
+
+        for (i = 0; i < steps; i++) {
+                if (avg_lum > desired_avg_lum) {
+                        if (gain > gain_knee)
+                                gain--;
+                        else if (exposure > exposure_knee)
+                                exposure--;
+                        else if (gain > gain_ctrl->qctrl.default_value)
+                                gain--;
+                        else if (exposure > exposure_ctrl->qctrl.minimum)
+                                exposure--;
+                        else if (gain > gain_ctrl->qctrl.minimum)
+                                gain--;
+                        else
+                                break;
+                } else {
+                        if (gain < gain_ctrl->qctrl.default_value)
+                                gain++;
+                        else if (exposure < exposure_knee)
+                                exposure++;
+                        else if (gain < gain_knee)
+                                gain++;
+                        else if (exposure < exposure_ctrl->qctrl.maximum)
+                                exposure++;
+                        else if (gain < gain_ctrl->qctrl.maximum)
+                                gain++;
+                        else
+                                break;
+                }
+        }
+
+        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;
+}
+EXPORT_SYMBOL(gspca_auto_gain_n_exposure);
+
 /* -- module insert / remove -- */
 static int __init gspca_init(void)
 {