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

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

Hej Sakari,

Tack för feedback.

On 2024-08-27 13:32:43 +0000, Sakari Ailus wrote:
> 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.

What do you mean by macro? To test for priv->max96724, a define for the 
register name or something else?

> 
> >  
> >  	/* 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.

Good idea, will do so in next version.

> 
> >  	{ /* sentinel */ },
> >  };
> >  MODULE_DEVICE_TABLE(of, max96712_of_table);
> > 
> 
> -- 
> Trevliga hälsningar,
> 
> Sakari Ailus

-- 
Kind Regards,
Niklas Söderlund