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Subject[PATCH 4.19 074/187] cpufreq: acpi-cpufreq: Report if CPU doesnt support boost technologies
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 1222d527f314c86a3b59a522115d62facc5a7965 ]

There is some rare cases where CPB (and possibly IDA) are missing on
processors.

This is the case fixed by commit f7f3dc00f612 ("x86/cpu/AMD: Fix
erratum 1076 (CPB bit)") and following.

In such context, the boost status isn't reported by
/sys/devices/system/cpu/cpufreq/boost.

This commit is about printing a message to report that the CPU
doesn't expose the boost capabilities.

This message could help debugging platforms hit by this phenomena.

Signed-off-by: Erwan Velu <e.velu@criteo.com>
[ rjw: Change the message text somewhat ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cpufreq/acpi-cpufreq.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index b61f4ec43e06..aca30f45172e 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -911,8 +911,10 @@ static void __init acpi_cpufreq_boost_init(void)
{
int ret;

- if (!(boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA)))
+ if (!(boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA))) {
+ pr_debug("Boost capabilities not present in the processor\n");
return;
+ }

acpi_cpufreq_driver.set_boost = set_boost;
acpi_cpufreq_driver.boost_enabled = boost_state(0);
--
2.19.1


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