Hi Laurent
On Sat, Jan 01, 2022 at 08:28:04PM +0200, Laurent Pinchart wrote:
> Read the maxim,i2c-clock-frequency DT property that specifies the speed
> of the remote I2C bus, and configure the MAX9286 accordingly. The remote
> serializers must all have a matching configuration.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/i2c/max9286.c | 56 +++++++++++++++++++++++++++++++------
> 1 file changed, 47 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> index 4b69bd036ca6..d88a4d8e63ab 100644
> --- a/drivers/media/i2c/max9286.c
> +++ b/drivers/media/i2c/max9286.c
> @@ -143,6 +143,11 @@ struct max9286_format_info {
> u8 datatype;
> };
>
> +struct max9286_i2c_speed {
> + u32 rate;
> + u8 mstbt;
> +};
> +
> struct max9286_source {
> struct v4l2_subdev *sd;
> struct fwnode_handle *fwnode;
> @@ -176,6 +181,7 @@ struct max9286_priv {
> /* The initial reverse control channel amplitude. */
> u32 init_rev_chan_mv;
> u32 rev_chan_mv;
> + u8 i2c_mstbt;
>
> struct v4l2_ctrl_handler ctrls;
> struct v4l2_ctrl *pixelrate_ctrl;
> @@ -250,6 +256,17 @@ static const struct max9286_format_info max9286_formats[] = {
> },
> };
>
> +static const struct max9286_i2c_speed max9286_i2c_speeds[] = {
> + { .rate = 8470, .mstbt = MAX9286_I2CMSTBT_8KBPS },
> + { .rate = 28300, .mstbt = MAX9286_I2CMSTBT_28KBPS },
> + { .rate = 84700, .mstbt = MAX9286_I2CMSTBT_84KBPS },
> + { .rate = 105000, .mstbt = MAX9286_I2CMSTBT_105KBPS },
> + { .rate = 173000, .mstbt = MAX9286_I2CMSTBT_173KBPS },
> + { .rate = 339000, .mstbt = MAX9286_I2CMSTBT_339KBPS },
> + { .rate = 533000, .mstbt = MAX9286_I2CMSTBT_533KBPS },
> + { .rate = 837000, .mstbt = MAX9286_I2CMSTBT_837KBPS },
> +};
> +
> /* -----------------------------------------------------------------------------
> * I2C IO
> */
> @@ -370,7 +387,7 @@ static int max9286_i2c_mux_init(struct max9286_priv *priv)
> static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
> {
> u8 config = MAX9286_I2CSLVSH_469NS_234NS | MAX9286_I2CSLVTO_1024US |
Does the 'slave remote timeout' need to be changed according to speed
as well ?
> - MAX9286_I2CMSTBT_105KBPS;
> + priv->i2c_mstbt;
>
> if (localack)
> config |= MAX9286_I2CLOCACK;
> @@ -1320,6 +1337,8 @@ static int max9286_parse_dt(struct max9286_priv *priv)
> struct device_node *node = NULL;
> unsigned int i2c_mux_mask = 0;
> u32 reverse_channel_microvolt;
> + u32 i2c_clk_freq = 105000;
> + unsigned int i;
>
> /* Balance the of_node_put() performed by of_find_node_by_name(). */
> of_node_get(dev->of_node);
> @@ -1410,6 +1429,23 @@ static int max9286_parse_dt(struct max9286_priv *priv)
> }
> of_node_put(node);
>
> + of_property_read_u32(dev->of_node, "maxim,i2c-clock-frequency",
> + &i2c_clk_freq);
> + for (i = 0; i < ARRAY_SIZE(max9286_i2c_speeds); ++i) {
> + const struct max9286_i2c_speed *speed = &max9286_i2c_speeds[i];
> +
> + if (speed->rate == i2c_clk_freq) {
> + priv->i2c_mstbt = speed->mstbt;
> + break;
> + }
> + }
> +
> + if (i == ARRAY_SIZE(max9286_i2c_speeds)) {
> + dev_err(dev, "Invalid %s value %u\n",
> + "maxim,i2c-clock-frequency", i2c_clk_freq);
> + return -EINVAL;
> + }
> +
I never got a real answer to this question in years: should we assume
dts are correct or should we validate them ?
> /*
> * Parse the initial value of the reverse channel amplitude from
> * the firmware interface and convert it to millivolts.
> @@ -1484,10 +1520,16 @@ static int max9286_probe(struct i2c_client *client)
> priv->client = client;
> i2c_set_clientdata(client, priv);
>
> + ret = max9286_parse_dt(priv);
Any reason why moving this so up ? Doing so just before i2c_config()
would be enough ?
> + if (ret)
> + goto err_cleanup_dt;
> +
> priv->gpiod_pwdn = devm_gpiod_get_optional(&client->dev, "enable",
> GPIOD_OUT_HIGH);
> - if (IS_ERR(priv->gpiod_pwdn))
> - return PTR_ERR(priv->gpiod_pwdn);
> + if (IS_ERR(priv->gpiod_pwdn)) {
> + ret = PTR_ERR(priv->gpiod_pwdn);
> + goto err_cleanup_dt;
> + }
>
> gpiod_set_consumer_name(priv->gpiod_pwdn, "max9286-pwdn");
> gpiod_set_value_cansleep(priv->gpiod_pwdn, 1);
> @@ -1514,10 +1556,6 @@ static int max9286_probe(struct i2c_client *client)
> if (ret)
> goto err_powerdown;
>
> - ret = max9286_parse_dt(priv);
> - if (ret)
> - goto err_cleanup_dt;
> -
> ret = max9286_get_poc_supplies(priv);
> if (ret)
> goto err_cleanup_dt;
> @@ -1528,10 +1566,10 @@ static int max9286_probe(struct i2c_client *client)
>
> return 0;
>
> -err_cleanup_dt:
> - max9286_cleanup_dt(priv);
> err_powerdown:
> gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
> +err_cleanup_dt:
> + max9286_cleanup_dt(priv);
>
> return ret;
> }
> --
> Regards,
>
> Laurent Pinchart
>
