[PATCH] firmware: arm_scmi: Warn if domain frequency multiplier is 0 or rounded off

[Cristian Marussi]

On Fri, Jan 19, 2024 at 11:10:33AM +0000, Sudeep Holla wrote:
> When (sustained_freq_khz * 1000) is less than sustained_perf_level, the
> multiplier will be less than 1 and hence rounded down as 0. Similarly if
> it is not multiple of sustained_perf_level the dom_info->mult_factor will
> contain rounded down value and will end up impacting all the frequency
> calculations done using it.
> 
> Add warning if and when the domain frequency multiplier is 0 or rounded
> down so that it gives a clue to get the firmware tables fixed.
> 

Hi,

just one small nitpick down below...

> Suggested-by: Pierre Gondois <Pierre.Gondois at arm.com>
> Cc: Cristian Marussi <cristian.marussi at arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
>  drivers/firmware/arm_scmi/perf.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index 8ea2a7b3d35d..5a7358e89d6f 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -272,13 +272,21 @@ scmi_perf_domain_attributes_get(const struct scmi_protocol_handle *ph,
>  					le32_to_cpu(attr->sustained_perf_level);
>  		if (!dom_info->sustained_freq_khz ||
>  		    !dom_info->sustained_perf_level ||
> -		    dom_info->level_indexing_mode)
> +		    dom_info->level_indexing_mode) {
>  			/* CPUFreq converts to kHz, hence default 1000 */
>  			dom_info->mult_factor =	1000;
> -		else
> +		} else {
>  			dom_info->mult_factor =
>  					(dom_info->sustained_freq_khz * 1000UL)
>  					/ dom_info->sustained_perf_level;
> +			if ((dom_info->sustained_freq_khz * 1000UL) %
> +			    dom_info->sustained_perf_level)
> +				pr_warn("mult_factor of domain %d is rounded\n",
> +					dom_info->id);

...here you can use dev_warn(ph->dev, ...) if you want.

Other than that, LGTM.

Reviewed-by: Cristian Marussi <cristian.marussi at arm.com>

Thanks,
Cristian