Re: [PATCH v13 10/12] iio: frequency: adf41513: features on frequency change

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The calculated `bleed_value` can exceed the 8-bit maximum of `ADF41513_REG6_BLEED_CURRENT_MSK`, causing silent truncation when written.
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commit ca2e85652223c6f4917441bebff8f2b7161b211f
Author: Rodrigo Alencar <rodrigo.alencar@analog.com>

iio: frequency: adf41513: features on frequency change
    
Set Bleed current when PFD frequency changes (bleed enabled when in
fractional mode). Set lock detector window size, handling bias and
precision. Add phase resync support, setting clock dividers when
PFD frequency changes.

> diff --git a/drivers/iio/frequency/adf41513.c b/drivers/iio/frequency/adf41513.c
> --- a/drivers/iio/frequency/adf41513.c
> +++ b/drivers/iio/frequency/adf41513.c

[ ... ]

> @@ -579,9 +595,83 @@ static int adf41513_calc_pll_settings(struct adf41513_state *st,
>  	return 0;
>  }
>  
> +static void adf41513_set_bleed_val(struct adf41513_state *st)
> +{
> +	u32 bleed_value, cp_index;
> +
> +	if (st->data.phase_detector_polarity)
> +		bleed_value = 90;
> +	else
> +		bleed_value = 144;
> +
> +	cp_index = 1 + FIELD_GET(ADF41513_REG5_CP_CURRENT_MSK,
> +				 st->regs[ADF41513_REG5]);
> +	bleed_value = div64_u64(st->settings.pfd_frequency_uhz * cp_index * bleed_value,
> +				1600ULL * MEGA * MICROHZ_PER_HZ);
> +
> +	FIELD_MODIFY(ADF41513_REG6_BLEED_CURRENT_MSK, &st->regs[ADF41513_REG6],
> +		     bleed_value);

Can bleed_value exceed the 8-bit maximum of ADF41513_REG6_BLEED_CURRENT_MSK?

In Integer-N mode, pfd_frequency_uhz can reach 250 MHz (250e12 uHz). Combined
with a maximum cp_index of 16 and a phase detector polarity base value of 144,
the formula yields 360 ((250e12 * 16 * 144) / 1.6e15).

Since ADF41513_REG6_BLEED_CURRENT_MSK is an 8-bit mask (max value 255),
writing 360 via FIELD_MODIFY silently truncates the value to 104.

While this doesn't cause immediate functional harm because the bleed current
is explicitly disabled in Integer-N mode, should this calculation be clamped
or skipped completely when bleed is disabled to prevent writing a wrapped
value?

> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260517-adf41513-iio-driver-v13-0-bb6e134a360f@analog.com?part=10