linux-kernel - Re: [PATCH 3/8] ACPI: CPPC: Adjust debug messages in amd_set_max_freq

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Message-ID: <d1222c30-114b-4f56-8805-600236b2684c@amd.com>
Date: Tue, 27 Aug 2024 13:48:47 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: "Gautham R. Shenoy" <gautham.shenoy@....com>,
 Mario Limonciello <superm1@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>, Perry Yuan <perry.yuan@....com>,
 "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
 "Rafael J . Wysocki" <rafael@...nel.org>,
 "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
 <linux-kernel@...r.kernel.org>, "open list:ACPI"
 <linux-acpi@...r.kernel.org>,
 "open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 3/8] ACPI: CPPC: Adjust debug messages in
 amd_set_max_freq_ratio() to warn

On 8/27/2024 09:50, Gautham R. Shenoy wrote:
> On Mon, Aug 26, 2024 at 04:13:53PM -0500, Mario Limonciello wrote:
>> From: Mario Limonciello <mario.limonciello@....com>
>>
>> If the boost ratio isn't calculated properly for the system for any
>> reason this can cause other problems that are non-obvious.
>>
>> Raise all messages to warn instead.
>>
>> Suggested-by: Perry Yuan <Perry.Yuan@....com>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>>   arch/x86/kernel/acpi/cppc.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
>> index 1d631ac5ec328..e94507110ca24 100644
>> --- a/arch/x86/kernel/acpi/cppc.c
>> +++ b/arch/x86/kernel/acpi/cppc.c
>> @@ -75,17 +75,17 @@ static void amd_set_max_freq_ratio(void)
>>   
>>   	rc = cppc_get_perf_caps(0, &perf_caps);
>>   	if (rc) {
>> -		pr_debug("Could not retrieve perf counters (%d)\n", rc);
>> +		pr_warn("Could not retrieve perf counters (%d)\n", rc);
>>   		return;
>>   	}
>>   
>>   	rc = amd_get_boost_ratio_numerator(0, &highest_perf);
>>   	if (rc)
>> -		pr_debug("Could not retrieve highest performance\n");
>> +		pr_warn("Could not retrieve highest performance\n");
>>   	nominal_perf = perf_caps.nominal_perf;
>>   
>>   	if (!nominal_perf) {
>> -		pr_debug("Could not retrieve nominal performance\n");
>> +		pr_warn("Could not retrieve nominal performance\n");
>>   		return;
>>   	}
>>   
>> @@ -93,7 +93,7 @@ static void amd_set_max_freq_ratio(void)
>>   	/* midpoint between max_boost and max_P */
>>   	perf_ratio = (perf_ratio + SCHED_CAPACITY_SCALE) >> 1;
>>   	if (!perf_ratio) {
>> -		pr_debug("Non-zero highest/nominal perf values led to a 0 ratio\n");
>> +		pr_warn("Non-zero highest/nominal perf values led to a 0 ratio\n");
>>   		return;
> 
> Aside:
> perf_ratio is a u64, and SCHED_CAPACITY_SCALE is (1L << 10). Thus, is
> it even possible to have !perf_ratio?
> 
> Otherwise, I am ok with this promotion of pr_debug to pr_warn.

You're right; I don't see this is possible.  I'll tear it out in a 
prerequisite patch in v2.

> 
> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>
> 
> --
> Thanks and Regards
> gautham.