diff mbox series

[v2,09/11] media: i2c: max9286: Configure remote I2C speed from device tree

Message ID 20220101182806.19311-10-laurent.pinchart+renesas@ideasonboard.com (mailing list archive)
State New, archived
Headers show
Series media: i2c: max9286: Small new features | expand

Commit Message

Laurent Pinchart Jan. 1, 2022, 6:28 p.m. UTC 
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@ideasonboard.com>
---
 drivers/media/i2c/max9286.c | 56 +++++++++++++++++++++++++++++++------
 1 file changed, 47 insertions(+), 9 deletions(-)

Comments

Jacopo Mondi Jan. 9, 2022, 10:43 a.m. UTC | #1 
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@ideasonboard.com>
> ---
>  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
>
Laurent Pinchart Jan. 9, 2022, 11:29 p.m. UTC | #2 
Hi Jacopo,

On Sun, Jan 09, 2022 at 11:43:32AM +0100, Jacopo Mondi wrote:
> 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@ideasonboard.com>
> > ---
> >  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 ?

Possibly, but the documentation doesn't tell how, and the current values
for the setup/hold times and the timeout work fine in my setup, so I
haven't changed them.

> > -		    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 ?

That's a very good question :-) Given the DT-is-an-ABI dogma, I tend to
do validation in drivers, to avoid accepting incorrect device trees that
would work by chance and find myself unable to fix the driver later.

> >  	/*
> >  	 * 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 ?

Just to avoid having to move it up again in the future if we add more
parameters to the device tree that would be needed before
max9286_configure_i2c().

> > +	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;
> >  }
diff mbox series

Patch

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 |
-		    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;
+	}
+
 	/*
 	 * 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);
+	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;
 }