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cpufreq/amd-pstate: Remove warning for X86_FEATURE_CPPC on certain Zen models

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commit bff7d13c19 ("cpufreq: amd-pstate: add debug message while
CPPC is supported and disabled by SBIOS") issues a warning on plaforms
where the X86_FEATURE_CPPC is expected to be enabled, but is not due
to it being disabled in the BIOS.

This feature bit corresponds to CPUID 0x80000008.ebx[27] which is a
reserved bit on the Zen1 processors and a reserved bit on Zen2 based
models 0x70-0x7F, and is expected to be cleared on these
platforms. Thus printing the warning message for these models when
X86_FEATURE_CPPC is unavailable is incorrect. Fix this.

Modify some of the comments, and use switch-case for model range
checking for improved readability while at it.

Fixes: bff7d13c19 ("cpufreq: amd-pstate: add debug message while CPPC is supported and disabled by SBIOS")
Cc: Xiaojian Du <xiaojian.du@amd.com>
Reported-by: David Wang <00107082@163.com>
Closes: https://lore.kernel.org/lkml/20240730140111.4491-1-00107082@163.com/
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Acked-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
This commit is contained in:
Gautham R. Shenoy 2024-08-28 15:40:35 +05:30 committed by Mario Limonciello
parent 9983a9cd4d
commit 9c68a3b03e
1 changed files with 24 additions and 10 deletions
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34
drivers/cpufreq/amd-pstate.c
View file

@ -1834,20 +1834,34 @@ static bool amd_cppc_supported(void)
}
/*
* If the CPPC feature is disabled in the BIOS for processors that support MSR-based CPPC,
* the AMD Pstate driver may not function correctly.
* Check the CPPC flag and display a warning message if the platform supports CPPC.
* Note: below checking code will not abort the driver registeration process because of
* the code is added for debugging purposes.
* If the CPPC feature is disabled in the BIOS for processors
* that support MSR-based CPPC, the AMD Pstate driver may not
* function correctly.
*
* For such processors, check the CPPC flag and display a
* warning message if the platform supports CPPC.
*
* Note: The code check below will not abort the driver
* registration process because of the code is added for
* debugging purposes. Besides, it may still be possible for
* the driver to work using the shared-memory mechanism.
*/
if (!cpu_feature_enabled(X86_FEATURE_CPPC)) {
if (cpu_feature_enabled(X86_FEATURE_ZEN1) || cpu_feature_enabled(X86_FEATURE_ZEN2)) {
if (c->x86_model > 0x60 && c->x86_model < 0xaf)
if (cpu_feature_enabled(X86_FEATURE_ZEN2)) {
switch (c->x86_model) {
case 0x60 ... 0x6F:
case 0x80 ... 0xAF:
warn = true;
} else if (cpu_feature_enabled(X86_FEATURE_ZEN3) || cpu_feature_enabled(X86_FEATURE_ZEN4)) {
if ((c->x86_model > 0x10 && c->x86_model < 0x1F) ||
(c->x86_model > 0x40 && c->x86_model < 0xaf))
break;
}
} else if (cpu_feature_enabled(X86_FEATURE_ZEN3) ||
cpu_feature_enabled(X86_FEATURE_ZEN4)) {
switch (c->x86_model) {
case 0x10 ... 0x1F:
case 0x40 ... 0xAF:
warn = true;
break;
}
} else if (cpu_feature_enabled(X86_FEATURE_ZEN5)) {
warn = true;
}