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authorJacopo Mondi <jacopo+renesas@jmondi.org>2021-01-14 20:04:28 +0300
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>2021-02-06 11:33:45 +0300
commit5a386b1ff7710dec76c586a3e79f862fc9fc9d73 (patch)
treed04c48dc033ddc8f1ce608a2f1531c2dc5f14782 /drivers/media
parent02b57eb3b5760520154f6c1b7db4e58a1780f3b6 (diff)
downloadlinux-5a386b1ff7710dec76c586a3e79f862fc9fc9d73.tar.xz
media: i2c: max9286: Make channel amplitude programmable
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. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'drivers/media')
-rw-r--r--drivers/media/i2c/max9286.c21
1 files changed, 15 insertions, 6 deletions
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index ebe9c2215b48..4d7587dfb5aa 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -336,19 +336,28 @@ static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
usleep_range(3000, 5000);
}
-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 to express values (100 < x < 130) */
+ chan_amplitude = max(30U, 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 +966,7 @@ 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