Re: [PATCH v2 2/2] media: staging: max96712: Add support for MAX96724

[Sakari Ailus <sakari.ailus@iki.fi>]

Hejssan,

Tack för lappan!

On Tue, Aug 27, 2024 at 03:18:41PM +0200, Niklas Söderlund wrote:
> The MAX96724 is almost identical to the MAX96712 and can be supported by
> the same driver, add support for it.
> 
> For the staging driver which only supports patter generation the big
> difference is that the datasheet (rev 4) for MAX96724 do not describe
> the DEBUG_EXTRA register, which is at offset 0x0009 on MAX96712. It's
> not clear if this register is removed or moved to a different offset.
> What is known is writing to register 0x0009 have no effect on MAX96724.
> 
> This makes it impossible to increase the test pattern clock frequency
> from 25 MHz to 75Mhz on MAX96724. To be able to get a stable test
> pattern the DPLL frequency have to be increase instead to compensate for
> this. The frequency selected is found by experimentation as the MAX96724
> datasheet is much sparser then what's available for MAX96712.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
> * Changes since v1
> - Group in series together with binding.
> ---
>  drivers/staging/media/max96712/max96712.c | 26 ++++++++++++++++++-----
>  1 file changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/media/max96712/max96712.c b/drivers/staging/media/max96712/max96712.c
> index 6bdbccbee05a..6bd02276c413 100644
> --- a/drivers/staging/media/max96712/max96712.c
> +++ b/drivers/staging/media/max96712/max96712.c
> @@ -17,8 +17,10 @@
>  #include <media/v4l2-subdev.h>
>  
>  #define MAX96712_ID 0x20
> +#define MAX96724_ID 0xA7
>  
>  #define MAX96712_DPLL_FREQ 1000
> +#define MAX96724_DPLL_FREQ 1200
>  
>  enum max96712_pattern {
>  	MAX96712_PATTERN_CHECKERBOARD = 0,
> @@ -31,6 +33,7 @@ struct max96712_priv {
>  	struct gpio_desc *gpiod_pwdn;
>  
>  	bool cphy;
> +	bool max96724;
>  	struct v4l2_mbus_config_mipi_csi2 mipi;
>  
>  	struct v4l2_subdev sd;
> @@ -120,6 +123,7 @@ static void max96712_mipi_enable(struct max96712_priv *priv, bool enable)
>  
>  static void max96712_mipi_configure(struct max96712_priv *priv)
>  {
> +	unsigned int dpll_freq;
>  	unsigned int i;
>  	u8 phy5 = 0;
>  
> @@ -152,10 +156,11 @@ static void max96712_mipi_configure(struct max96712_priv *priv)
>  	max96712_write(priv, 0x8a5, phy5);
>  
>  	/* Set link frequency for PHY0 and PHY1. */
> +	dpll_freq = priv->max96724 ? MAX96724_DPLL_FREQ : MAX96712_DPLL_FREQ;
>  	max96712_update_bits(priv, 0x415, 0x3f,
> -			     ((MAX96712_DPLL_FREQ / 100) & 0x1f) | BIT(5));
> +			     ((dpll_freq / 100) & 0x1f) | BIT(5));
>  	max96712_update_bits(priv, 0x418, 0x3f,
> -			     ((MAX96712_DPLL_FREQ / 100) & 0x1f) | BIT(5));
> +			     ((dpll_freq / 100) & 0x1f) | BIT(5));
>  
>  	/* Enable PHY0 and PHY1 */
>  	max96712_update_bits(priv, 0x8a2, 0xf0, 0x30);
> @@ -181,7 +186,8 @@ static void max96712_pattern_enable(struct max96712_priv *priv, bool enable)
>  	}
>  
>  	/* PCLK 75MHz. */
> -	max96712_write(priv, 0x0009, 0x01);
> +	if (!priv->max96724)
> +		max96712_write(priv, 0x0009, 0x01);

It'd be nice to have a macro for this, espeically now that the driver
supports more than one chip.

>  
>  	/* Configure Video Timing Generator for 1920x1080 @ 30 fps. */
>  	max96712_write_bulk_value(priv, 0x1052, 0, 3);
> @@ -303,6 +309,7 @@ static const struct v4l2_ctrl_ops max96712_ctrl_ops = {
>  
>  static int max96712_v4l2_register(struct max96712_priv *priv)
>  {
> +	unsigned int dpll_freq;
>  	long pixel_rate;
>  	int ret;
>  
> @@ -317,7 +324,8 @@ static int max96712_v4l2_register(struct max96712_priv *priv)
>  	 * TODO: Once V4L2_CID_LINK_FREQ is changed from a menu control to an
>  	 * INT64 control it should be used here instead of V4L2_CID_PIXEL_RATE.
>  	 */
> -	pixel_rate = MAX96712_DPLL_FREQ / priv->mipi.num_data_lanes * 1000000;
> +	dpll_freq = priv->max96724 ? MAX96724_DPLL_FREQ : MAX96712_DPLL_FREQ;
> +	pixel_rate = dpll_freq / priv->mipi.num_data_lanes * 1000000;
>  	v4l2_ctrl_new_std(&priv->ctrl_handler, NULL, V4L2_CID_PIXEL_RATE,
>  			  pixel_rate, pixel_rate, 1, pixel_rate);
>  
> @@ -438,8 +446,15 @@ static int max96712_probe(struct i2c_client *client)
>  	if (priv->gpiod_pwdn)
>  		usleep_range(4000, 5000);
>  
> -	if (max96712_read(priv, 0x4a) != MAX96712_ID)
> +	switch (max96712_read(priv, 0x4a)) {
> +	case MAX96712_ID:
> +		break;
> +	case MAX96724_ID:
> +		priv->max96724 = true;
> +		break;
> +	default:
>  		return -ENODEV;
> +	}
>  
>  	max96712_reset(priv);
>  
> @@ -463,6 +478,7 @@ static void max96712_remove(struct i2c_client *client)
>  
>  static const struct of_device_id max96712_of_table[] = {
>  	{ .compatible = "maxim,max96712" },
> +	{ .compatible = "maxim,max96724" },

How about adding compatible specific data to convey the model, instead of a
switch? See e.g. drivers/media/i2c/ccs/ccs-core.c for an example.

You could store the DPLL frequency there, too.

>  	{ /* sentinel */ },
>  };
>  MODULE_DEVICE_TABLE(of, max96712_of_table);
> 

-- 
Trevliga hälsningar,

Sakari Ailus