Hi Jacopo,
On 16/03/2020 20:27, Jacopo Mondi wrote:
> Parse the 'maxim,reverse-channel-amplitude' property value and cache its
> content to later program the initial reverse channel amplitude.
>
> Only support 100mV and 170mV values for the moment. The property could
> be easily expanded to support more values.
Can we (in the future) support arbitrary values from a range, or only
from a fixed list?
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> drivers/media/i2c/max9286.c | 39 ++++++++++++++++++++++++++++++++-----
> 1 file changed, 34 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> index 0357515860b2..24af8002535e 100644
> --- a/drivers/media/i2c/max9286.c
> +++ b/drivers/media/i2c/max9286.c
> @@ -168,6 +168,7 @@ struct max9286_priv {
> struct max9286_source sources[MAX9286_NUM_GMSL];
> struct v4l2_async_notifier notifier;
>
> + u32 reverse_chan_amp;
> u32 overlap_window;
> };
>
> @@ -479,10 +480,15 @@ static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
> * All enabled sources have probed and enabled their reverse control
> * channels:
> *
> - * - Verify all configuration links are properly detected
> + * - Increase reverse channel amplitude to 170mV if not initially
> + * compensated
> * - Disable auto-ack as communication on the control channel are now
> * stable.
> */
> + if (priv->reverse_chan_amp == 100)
> + max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) |
> + MAX9286_REV_AMP(70) | MAX9286_REV_AMP_X);
> +
> max9286_check_config_link(priv, priv->source_mask);
>
> /*
> @@ -830,6 +836,8 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv)
>
> static int max9286_setup(struct max9286_priv *priv)
> {
> + u8 chan_amp = MAX9286_REV_TRF(1);
> +
> /*
> * Link ordering values for all enabled links combinations. Orders must
> * be assigned sequentially from 0 to the number of enabled links
> @@ -869,12 +877,18 @@ static int max9286_setup(struct max9286_priv *priv)
> *
> * - 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.
> + * - Set initial reverse channel amplitude according the DTS property.
> + * If the initial channel amplitude is 100mV it should be increase
> + * later after the serializers high threshold have been enabled.
> + * If the initial value is 170mV the serializer has been
> + * pre-programmed and we can compensate immediately.> */
> 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 (priv->reverse_chan_amp == 100)
> + chan_amp |= MAX9286_REV_AMP(100);
> + else
> + chan_amp |= MAX9286_REV_AMP(70) | MAX9286_REV_AMP_X;
> + max9286_write(priv, 0x3b, chan_amp);
> usleep_range(2000, 2500);
>
> /*
> @@ -1069,6 +1083,21 @@ static int max9286_parse_dt(struct max9286_priv *priv)
> return -EINVAL;
> }
>
> + ret = of_property_read_u32(dev->of_node, "maxim,reverse-channel-amplitude",
> + &priv->reverse_chan_amp);
> + if (ret) {
> + dev_err(dev,
> + "Missing property \"maxim,reverse-channel-amplitude\"\n");
> + of_node_put(dev->of_node);
> + return -EINVAL;
> + }
> + if (priv->reverse_chan_amp != 100 && priv->reverse_chan_amp != 170) {
> + dev_err(dev, "Unsupported channel amplitude %umV\n",
> + priv->reverse_chan_amp);
> + of_node_put(dev->of_node);
> + return -EINVAL;
> + }
> +
> i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> if (!i2c_mux) {
> dev_err(dev, "Failed to find i2c-mux node\n");
>
