Re: [PATCH v1 1/1] iio: adc: nxp-sar-adc: Fix the delay calculation in nxp_sar_adc_wait_for()

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 19 May 2026 23:56:06 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> The original code was using ndelay() twice. In one case the delay
> is calculated as 1/3 of ADC clock and in the other as 80 ADC clocks.
> But according to the comments in all cases it should be a multiplier
> of the ADC clock, and not a fraction of it. Inadvertently
> nxp_sar_adc_wait_for() takes the wrong case and spread it over
> the code make it wrong in all places. Fix this by modifying a helper
> to correctly use the multiplier.
> 
> Fixes: 7e5c0f97c66a ("iio: adc: nxp-sar-adc: Avoid division by zero")
> Fixes: 4434072a893e ("iio: adc: Add the NXP SAR ADC support for the s32g2/3 platforms")
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://sashiko.dev/#/patchset/20260416090122.758990-1-andriy.shevchenko%40linux.intel.com
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Daniel, could you take a look at this one.

Explanation seems fine but original patch was yours so I'd like
some 'aware' eyes on it!

> ---
>  drivers/iio/adc/nxp-sar-adc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/nxp-sar-adc.c b/drivers/iio/adc/nxp-sar-adc.c
> index 01f3da56e987..68d237ef30c2 100644
> --- a/drivers/iio/adc/nxp-sar-adc.c
> +++ b/drivers/iio/adc/nxp-sar-adc.c
> @@ -198,13 +198,13 @@ static void nxp_sar_adc_irq_cfg(struct nxp_sar_adc *info, bool enable)
>  		writel(0, NXP_SAR_ADC_IMR(info->regs));
>  }
>  
> -static void nxp_sar_adc_wait_for(struct nxp_sar_adc *info, unsigned int cycles)
> +static void nxp_sar_adc_wait_for(struct nxp_sar_adc *info, u64 cycles)
>  {
>  	u64 rate;
>  
>  	rate = clk_get_rate(info->clk);
>  	if (rate)
> -		ndelay(div64_u64(NSEC_PER_SEC, rate * cycles));
> +		ndelay(div64_u64(NSEC_PER_SEC * cycles, rate));
>  }
>  
>  static bool nxp_sar_adc_set_enabled(struct nxp_sar_adc *info, bool enable)