linux-kernel - Re: [PATCH 1/2] firmware: arm_scmi: Fix frequency truncation by promoting multiplier to u64

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Message-ID: <20231201143935.be6wzjzxmyl5vpz6@bogus>
Date:   Fri, 1 Dec 2023 14:39:35 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     quic_mdtipton@...cinc.com, quic_asartor@...cinc.com,
        quic_lingutla@...cinc.com, Sibi Sankar <quic_sibis@...cinc.com>,
        linux-arm-msm@...r.kernel.org,
        Cristian Marussi <cristian.marussi@....com>
Subject: Re: [PATCH 1/2] firmware: arm_scmi: Fix frequency truncation by
 promoting multiplier to u64

On Thu, Nov 30, 2023 at 08:43:42PM +0000, Sudeep Holla wrote:
> Fix the frequency truncation for all values equal to or greater 4GHz by
> updating the multiplier 'mult_factor' to u64 type. It is also possible
> that the multiplier itself can be greater than or equal to 2^32. So we need
> to also fix the equation computing the value of the multiplier.
> 
> Fixes: a9e3fbfaa0ff ("firmware: arm_scmi: add initial support for performance protocol")
> Reported-by: Sibi Sankar <quic_sibis@...cinc.com>
> Closes: https://lore.kernel.org/all/20231129065748.19871-3-quic_sibis@quicinc.com/
> Cc: Cristian Marussi <cristian.marussi@....com>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/firmware/arm_scmi/perf.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index 81dd5c5e5533..8ce449922e55 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -152,7 +152,7 @@ struct perf_dom_info {
>  	u32 opp_count;
>  	u32 sustained_freq_khz;
>  	u32 sustained_perf_level;
> -	u32 mult_factor;
> +	u64 mult_factor;

I have now changed this to unsigned long instead of u64 to fix the 32-bit
build failure[1].

-- 
Regards,
Sudeep

[1] https://lore.kernel.org/all/20231201085914.4ad45eb2@canb.auug.org.au