Instrument the function that configures the reverse channel with a
programmable amplitude value.
This change serves to prepare to adjust the reverse channel amplitude
depending on the remote end high-threshold configuration.
Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
---
drivers/media/i2c/max9286.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 89a7248f5c25..163e102199e3 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -906,19 +906,29 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv)
* Probe/Remove
*/
-static void max9286_reverse_channel_setup(struct max9286_priv *priv)
+static void max9286_reverse_channel_setup(struct max9286_priv *priv,
+ unsigned int chan_amplitude)
{
+ /* Reverse channel transmission time: default to 1. */
+ u8 chan_config = MAX9286_REV_TRF(1);
+
/*
* Reverse channel setup.
*
* - Enable custom reverse channel configuration (through register 0x3f)
* and set the first pulse length to 35 clock cycles.
- * - Increase the reverse channel amplitude to 170mV to accommodate the
- * high threshold enabled by the serializer driver.
+ * - Adjust reverse channel amplitude: values > 130 are programmed
+ * using the additional +100mV REV_AMP_X boost flag
*/
max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));
- max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
- MAX9286_REV_AMP_X);
+
+ if (chan_amplitude > 100) {
+ /* It is not possible express values (100 < x < 130) */
+ chan_amplitude = chan_amplitude < 130
+ ? 30 : chan_amplitude - 100;
+ chan_config |= MAX9286_REV_AMP_X;
+ }
+ max9286_write(priv, 0x3b, chan_config | MAX9286_REV_AMP(chan_amplitude));
usleep_range(2000, 2500);
}
@@ -957,7 +967,7 @@ static int max9286_setup(struct max9286_priv *priv)
* only. This should be disabled after the mux is initialised.
*/
max9286_configure_i2c(priv, true);
- max9286_reverse_channel_setup(priv);
+ max9286_reverse_channel_setup(priv, 170);
/*
* Enable GMSL links, mask unused ones and autodetect link
--
2.28.0
