Provide a function to control setting of the overlap window, but disable
it by default.
The function will allow the value to be easily updated in the future,
either statically in the code, or via an external control mechanism.
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
---
drivers/media/i2c/max9286.c | 42 +++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 008a93910300..61178ae363d6 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -118,6 +118,9 @@
#define MAX9286_REV_FLEN(n) ((n) - 20)
/* Register 0x49 */
#define MAX9286_VIDEO_DETECT_MASK 0x0f
+/* Register 0x64 */
+#define MAX9286_ENFSINLAST BIT(5)
+#define MAX9286_OVLP_WINDOWH_MASK GENMASK(4, 0)
/* Register 0x69 */
#define MAX9286_LFLTBMONMASKED BIT(7)
#define MAX9286_LOCKMONMASKED BIT(6)
@@ -632,6 +635,34 @@ static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
return 0;
}
+/*
+ * The overlap window is a 13 bit value with the low byte in register 0x63 and
+ * the high byte(5bits) stored in the least significant bits of register 0x64.
+ */
+static int max9286_set_overlap_window(struct max9286_priv *priv, u16 window)
+{
+ int ret;
+ u8 val;
+
+ ret = max9286_read(priv, 0x64);
+ if (ret < 0)
+ return -EIO;
+
+ max9286_write(priv, 0x63, window & 0xff);
+
+ /*
+ * Process the high byte, while preserve existing bits set in 0x64.
+ * TODO: Convert this all to regmap so we can utilise regmap_update_bits
+ */
+ window >>= 8;
+ val = ret & ~MAX9286_OVLP_WINDOWH_MASK;
+ val |= window & MAX9286_OVLP_WINDOWH_MASK;
+
+ max9286_write(priv, 0x64, val);
+
+ return 0;
+}
+
static int max9286_set_pixelrate(struct max9286_priv *priv, s64 rate)
{
if (!priv->pixelrate)
@@ -942,6 +973,17 @@ static int max9286_setup(struct max9286_priv *priv)
max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
MAX9286_HVSRC_D14);
+ /*
+ * The overlap window seems to provide additional validation by tracking
+ * the delay between vsync and frame sync, generating an error if the
+ * delay is bigger than the programmed window, though it's not yet clear
+ * what value should be set.
+ *
+ * As it's an optional value and can be disabled, we do so by setting
+ * a 0 overlap value.
+ */
+ max9286_set_overlap_window(priv, 0);
+
/*
* Wait for 2ms to allow the link to resynchronize after the
* configuration change.
--
2.20.1
