media: i2c: imx258: Follow normal V4L2 behaviours for clipping exposure

V4L2 sensor drivers are expected are expected to clip the supported
exposure range based on the VBLANK configured.
IMX258 wasn't doing that as register 0x350 (FRM_LENGTH_CTL)
switches it to a mode where frame length tracks coarse exposure time.

Disable this mode and clip the range for V4L2_CID_EXPOSURE appropriately
based on V4L2_CID_VBLANK.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c
index 6065667..a034e66 100644 (file)
--- a/drivers/media/i2c/imx258.c
+++ b/drivers/media/i2c/imx258.c
@@ -32,15 +32,16 @@
 
 #define IMX258_REG_VTS                 0x0340
 
-/* HBLANK control - read only */
-#define IMX258_PPL_DEFAULT             5352
-
 /* Exposure control */
 #define IMX258_REG_EXPOSURE            0x0202
+#define IMX258_EXPOSURE_OFFSET         10
 #define IMX258_EXPOSURE_MIN            4
 #define IMX258_EXPOSURE_STEP           1
 #define IMX258_EXPOSURE_DEFAULT                0x640
-#define IMX258_EXPOSURE_MAX            65535
+#define IMX258_EXPOSURE_MAX            (IMX258_VTS_MAX - IMX258_EXPOSURE_OFFSET)
+
+/* HBLANK control - read only */
+#define IMX258_PPL_DEFAULT             5352
 
 /* Analog gain control */
 #define IMX258_REG_ANALOG_GAIN         0x0204
@@ -376,7 +377,7 @@ static const struct imx258_reg mode_4208x3120_regs[] = {
        { 0x034D, 0x70 },
        { 0x034E, 0x0C },
        { 0x034F, 0x30 },
-       { 0x0350, 0x01 },
+       { 0x0350, 0x00 },
        { 0x0204, 0x00 },
        { 0x0205, 0x00 },
        { 0x020E, 0x01 },
@@ -488,7 +489,7 @@ static const struct imx258_reg mode_2104_1560_regs[] = {
        { 0x034D, 0x38 },
        { 0x034E, 0x06 },
        { 0x034F, 0x18 },
-       { 0x0350, 0x01 },
+       { 0x0350, 0x00 },
        { 0x0204, 0x00 },
        { 0x0205, 0x00 },
        { 0x020E, 0x01 },
@@ -600,7 +601,7 @@ static const struct imx258_reg mode_1048_780_regs[] = {
        { 0x034D, 0x18 },
        { 0x034E, 0x03 },
        { 0x034F, 0x0C },
-       { 0x0350, 0x01 },
+       { 0x0350, 0x00 },
        { 0x0204, 0x00 },
        { 0x0205, 0x00 },
        { 0x020E, 0x01 },
@@ -934,6 +935,19 @@ static int imx258_update_digital_gain(struct imx258 *imx258, u32 len, u32 val)
        return 0;
 }
 
+static void imx258_adjust_exposure_range(struct imx258 *imx258)
+{
+       int exposure_max, exposure_def;
+
+       /* Honour the VBLANK limits when setting exposure. */
+       exposure_max = imx258->cur_mode->height + imx258->vblank->val -
+                      IMX258_EXPOSURE_OFFSET;
+       exposure_def = min(exposure_max, imx258->exposure->val);
+       __v4l2_ctrl_modify_range(imx258->exposure, imx258->exposure->minimum,
+                                exposure_max, imx258->exposure->step,
+                                exposure_def);
+}
+
 static int imx258_set_ctrl(struct v4l2_ctrl *ctrl)
 {
        struct imx258 *imx258 =
@@ -942,6 +956,13 @@ static int imx258_set_ctrl(struct v4l2_ctrl *ctrl)
        int ret = 0;
 
        /*
+        * The VBLANK control may change the limits of usable exposure, so check
+        * and adjust if necessary.
+        */
+       if (ctrl->id == V4L2_CID_VBLANK)
+               imx258_adjust_exposure_range(imx258);
+
+       /*
         * Applying V4L2 control value only happens
         * when power is up for streaming
         */