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| author |   Jacopo Mondi <jacopo+renesas@jmondi.org> | 2021-01-14 18:04:28 +0100 |
|---|---|---|
| committer |   Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2021-02-06 09:33:45 +0100 |
| commit | 5a386b1ff7710dec76c586a3e79f862fc9fc9d73 (patch) | |
| tree | d04c48dc033ddc8f1ce608a2f1531c2dc5f14782 /drivers/media | |
| parent | media: i2c: max9286: Break-out reverse channel setup (diff) | |
| download | linux-dev-5a386b1ff7710dec76c586a3e79f862fc9fc9d73.tar.xz linux-dev-5a386b1ff7710dec76c586a3e79f862fc9fc9d73.zip | |
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.c | 21 |
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 |