[PATCH] acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

[PATCH] acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

[Gautham R. Shenoy]

commit 083466754596 ("cpufreq: ACPI: Fix max-frequency computation")
modified get_max_boost_ratio() to return the nominal_freq advertised
in the _CPC object. This was for the purposes of computing the maximum
frequency. The frequencies advertised in _CPC objects are in
MHz. However, cpufreq expects the frequency to be in KHz. Since the
nominal_freq returned by get_max_boost_ratio() was not in KHz but
instead in MHz,the cpuinfo_max_frequency that was computed using this
nominal_freq was incorrect and an invalid value which resulted in
cpufreq reporting the P0 frequency as the cpuinfo_max_freq.

Fix this by converting the nominal_freq to KHz before returning the
same from get_max_boost_ratio().

Reported-by: Manu Bretelle <chantr4@gmail.com>
Closes: https://lore.kernel.org/lkml/aDaB63tDvbdcV0cg@HQ-GR2X1W2P57/
Fixes: 083466754596 ("cpufreq: ACPI: Fix max-frequency computation")
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
---
 drivers/cpufreq/acpi-cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index d26b610e4f24..76768fe213a9 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -660,7 +660,7 @@ static u64 get_max_boost_ratio(unsigned int cpu, u64 *nominal_freq)
 	nominal_perf = perf_caps.nominal_perf;
 
 	if (nominal_freq)
-		*nominal_freq = perf_caps.nominal_freq;
+		*nominal_freq = perf_caps.nominal_freq * 1000;
 
 	if (!highest_perf || !nominal_perf) {
 		pr_debug("CPU%d: highest or nominal performance missing\n", cpu);
-- 
2.34.1

Re: [PATCH] acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

[Rafael J. Wysocki]

On Thu, May 29, 2025 at 10:52 AM Gautham R. Shenoy
<gautham.shenoy@amd.com> wrote:
>
> commit 083466754596 ("cpufreq: ACPI: Fix max-frequency computation")
> modified get_max_boost_ratio() to return the nominal_freq advertised
> in the _CPC object. This was for the purposes of computing the maximum
> frequency. The frequencies advertised in _CPC objects are in
> MHz. However, cpufreq expects the frequency to be in KHz. Since the
> nominal_freq returned by get_max_boost_ratio() was not in KHz but
> instead in MHz,the cpuinfo_max_frequency that was computed using this
> nominal_freq was incorrect and an invalid value which resulted in
> cpufreq reporting the P0 frequency as the cpuinfo_max_freq.
>
> Fix this by converting the nominal_freq to KHz before returning the
> same from get_max_boost_ratio().
>
> Reported-by: Manu Bretelle <chantr4@gmail.com>
> Closes: https://lore.kernel.org/lkml/aDaB63tDvbdcV0cg@HQ-GR2X1W2P57/
> Fixes: 083466754596 ("cpufreq: ACPI: Fix max-frequency computation")
> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> ---
>  drivers/cpufreq/acpi-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index d26b610e4f24..76768fe213a9 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -660,7 +660,7 @@ static u64 get_max_boost_ratio(unsigned int cpu, u64 *nominal_freq)
>         nominal_perf = perf_caps.nominal_perf;
>
>         if (nominal_freq)
> -               *nominal_freq = perf_caps.nominal_freq;
> +               *nominal_freq = perf_caps.nominal_freq * 1000;
>
>         if (!highest_perf || !nominal_perf) {
>                 pr_debug("CPU%d: highest or nominal performance missing\n", cpu);
> --

Applied, thanks!

Re: [PATCH] acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

[Manu Bretelle]

On Thu, May 29, 2025 at 6:23 AM Rafael J. Wysocki <rafael@kernel.org> wrote:

>
> Applied, thanks!

Thanks Rafael!

I see it was merged into pm/linux-next, will it make it into the next
5.15 LTS release?
I did not find what the process is for LTS backport and would like to
make sure this trickles
down to LTS kernels.
Thanks

Re: [PATCH] acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

[Limonciello, Mario]

On 5/29/25 11:34 AM, Manu Bretelle wrote:
> On Thu, May 29, 2025 at 6:23 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
> 
>>
>> Applied, thanks!
> 
> Thanks Rafael!
> 
> I see it was merged into pm/linux-next, will it make it into the next
> 5.15 LTS release?
> I did not find what the process is for LTS backport and would like to
> make sure this trickles
> down to LTS kernels.
> Thanks

Here is the policy for stable:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html

It doesn't explicitly contain a stable tag, but because it has a fixes 
tag it's very likely that it gets backported by AUTOSEL later.

Re: [PATCH] acpi-cpufreq: Fix nominal_freq units to KHz in get_max_boost_ratio()

[Manu Bretelle]

> Here is the policy for stable:
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>
> It doesn't explicitly contain a stable tag, but because it has a fixes
> tag it's very likely that it gets backported by AUTOSEL later.
>
>
Thanks Mario!