Re: [PATCH v2 08/11] media: ccs-pll: Add a flag for even PLL multipliers

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

Thank you for the patch.

On Thu, Apr 17, 2025 at 09:53:51AM +0300, Sakari Ailus wrote:
> Some devices (not entirely CCS compliant) only support even PLL
> multipliers. Add support for this through a PLL flag.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/i2c/ccs-pll.c | 11 ++++++++++-
>  drivers/media/i2c/ccs-pll.h |  1 +
>  2 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/ccs-pll.c b/drivers/media/i2c/ccs-pll.c
> index ebbc5e323244..3f8153fb4af0 100644
> --- a/drivers/media/i2c/ccs-pll.c
> +++ b/drivers/media/i2c/ccs-pll.c
> @@ -124,9 +124,10 @@ static void print_pll(struct device *dev, const struct ccs_pll *pll)
>  	dev_dbg(dev, "pixel rate on CSI-2 bus:\t%u\n",
>  		pll->pixel_rate_csi);
>  
> -	dev_dbg(dev, "flags%s%s%s%s%s%s%s%s%s%s\n",
> +	dev_dbg(dev, "flags%s%s%s%s%s%s%s%s%s%s%s\n",
>  		pll->flags & PLL_FL(OP_PIX_CLOCK_PER_LANE) ? " op-pix-clock-per-lane" : "",
>  		pll->flags & PLL_FL(NO_OP_CLOCKS) ? " no-op-clocks" : "",
> +		pll->flags & PLL_FL(EVEN_PLL_MULTIPLIER) ? " even-pll-multiplier" : "",
>  		pll->flags & PLL_FL(LANE_SPEED_MODEL) ? " lane-speed" : "",
>  		pll->flags & PLL_FL(EXT_IP_PLL_DIVIDER) ?
>  		" ext-ip-pll-divider" : "",
> @@ -312,6 +313,10 @@ __ccs_pll_calculate_vt_tree(struct device *dev,
>  	more_mul *= DIV_ROUND_UP(lim_fr->min_pll_multiplier, mul * more_mul);
>  	dev_dbg(dev, "more_mul2: %u\n", more_mul);
>  
> +	if (pll->flags & CCS_PLL_FLAG_EVEN_PLL_MULTIPLIER &&
> +	    mul & 1 && more_mul & 1)

Even if not mandated by the C standard, I'd write

	    (mul & 1) && (more_mul & 1))

to make the code easier to read.

> +		more_mul <<= 1;

I'm not sure to get the logic behind this :-/

> +
>  	pll_fr->pll_multiplier = mul * more_mul;
>  	if (pll_fr->pll_multiplier > lim_fr->max_pll_multiplier) {
>  		dev_dbg(dev, "pll multiplier %u too high\n",
> @@ -668,6 +673,10 @@ ccs_pll_calculate_op(struct device *dev, const struct ccs_pll_limits *lim,
>  	if (!is_one_or_even(i))
>  		i <<= 1;
>  
> +	if (pll->flags & CCS_PLL_FLAG_EVEN_PLL_MULTIPLIER &&
> +	    mul & 1 && i & 1)

Same here.

> +		i <<= 1;
> +
>  	dev_dbg(dev, "final more_mul: %u\n", i);
>  	if (i > more_mul_max) {
>  		dev_dbg(dev, "final more_mul is bad, max %u\n", more_mul_max);
> diff --git a/drivers/media/i2c/ccs-pll.h b/drivers/media/i2c/ccs-pll.h
> index ee206e5b287b..e8297db45460 100644
> --- a/drivers/media/i2c/ccs-pll.h
> +++ b/drivers/media/i2c/ccs-pll.h
> @@ -31,6 +31,7 @@
>  #define CCS_PLL_FLAG_DUAL_PLL					BIT(8)
>  #define CCS_PLL_FLAG_OP_SYS_DDR					BIT(9)
>  #define CCS_PLL_FLAG_OP_PIX_DDR					BIT(10)
> +#define CCS_PLL_FLAG_EVEN_PLL_MULTIPLIER			BIT(11)

You could reuse bit 3, as it got dropped in patch 06/11.

>  
>  /**
>   * struct ccs_pll_branch_fr - CCS PLL configuration (front)

-- 
Regards,

Laurent Pinchart