Re: [PATCH v6 3/8] cpufreq:acpi:x86: Adjust the acpi-cpufreq.c code to work with common boost solution

On 26 July 2013 13:39, Lukasz Majewski [off-list ref] wrote:

On Fri, 26 Jul 2013 12:58:02 +0530 Viresh Kumar wrote,

quoted

On 25 July 2013 22:03, Lukasz Majewski [off-list ref] wrote:

quoted

diff --git a/drivers/cpufreq/acpi-cpufreq.c

b/drivers/cpufreq/acpi-cpufreq.c

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 static void __init acpi_cpufreq_boost_init(void)
 {
+       acpi_cpufreq_driver.boost_supported = false;

            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [*]

quoted

Would be better if we do this in else of below if.

We need to set boost_supported = false at [*] for the case when:
1. msrs_alloc fails
or
2. acpi_cpufreq is built as a module and can be inserted and removed
several times. Without [*] we could end up with wrong (not false)
initial state.

Hmm.. Now that I see the code again, we don't need to set it to false
as it is a global variable and this field is already set to false..

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        if (boot_cpu_has(X86_FEATURE_CPB) ||
boot_cpu_has(X86_FEATURE_IDA)) { msrs = msrs_alloc();

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@@ -1021,12 +995,11 @@ static int __init acpi_cpufreq_init(void)
                        *iter = &cpb;
        }
 #endif
+       acpi_cpufreq_boost_init();

            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [**]

quoted

We are calling it before registering cpufreq driver. Will this have
any complications?

When we call [**] after the cpufreq_register_driver [***] we end up with
sysfs boost attribute not exported at x86.
The boost attribute is exported at [***] only when
acpi_cpufreq.boost_supported = true. However support for boost at x86
is evaluated at acpi_cpufreq_boost_init().

I understand why you moved it above cpufreq driver register. I was thinking
if there can be few side effects of this..