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    SubjectRe: [PATCH v6 5/8] cpufreq:boost:Kconfig: Provide support for software managed BOOST
    On Fri, 26 Jul 2013 15:54:56 +0530 Viresh Kumar wrote,
    > On 25 July 2013 22:03, Lukasz Majewski <l.majewski@samsung.com> wrote:
    > > For safety reasons new flag - CONFIG_CPU_FREQ_BOOST_SW has been
    > > added. Only after selecting "EXYNOS Frequency Overclocking -
    > > Software" Kconfig
    >
    > You shouldn't mention Exynos here and must do exynos stuff at the end
    > in a separate patch. This one must be generic.

    Please see below comments.

    >
    > > option the software managed boost is enabled. It also selects
    > > thermal subsystem to be compiled in. Thermal is necessary for
    > > disabling boost and cooling down the device when overheating
    > > detected.
    > >
    > > Boost _MUST_NOT_ work without thermal subsystem with properly
    > > defined overheating temperatures.
    > >
    > > This option doesn't affect x86's ACPI hardware managed boost support
    > > (i.e. Intel, AMD). In this situation boost management is embedded at
    > > hardware.
    > >
    > > Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
    > > Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
    > >
    > > ---
    > > Changes for v6:
    > > - CPU_FREQ_BOOST_SW [1] is now defined as "invisible" bool option.
    > > - Platform dependent ARM_EXYNOS_CPU_FREQ_BOOST_SW config option has
    > > been added. It depends on ARM_EXYNOS_CPUFREQ options and selects
    > > EXYNOS_THERMAL with the main boost config [1].
    > >
    > > Changes for v5:
    > > - New patch
    > >
    > > drivers/cpufreq/Kconfig | 3 +++
    > > drivers/cpufreq/Kconfig.arm | 16 ++++++++++++++++
    > > 2 files changed, 19 insertions(+)
    > >
    > > diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
    > > index 534fcb8..3f058a3 100644
    > > --- a/drivers/cpufreq/Kconfig
    > > +++ b/drivers/cpufreq/Kconfig
    > > @@ -23,6 +23,9 @@ config CPU_FREQ_TABLE
    > > config CPU_FREQ_GOV_COMMON
    > > bool
    > >
    > > +config CPU_FREQ_BOOST_SW
    > > + bool
    >
    > Invisible is fine but this must be disabled by default and must
    > depend on thermal, rather than moving dependency on platform's
    > config.

    The CPU_FREQ_BOOST_SW [1] is a generic flag (invisible).

    I will add "default n" to it.
    It shall be used at all BOOST dependent #ifdefs (generic + platform).



    Also I've introduced the ARM_EXYNOS_CPU_FREQ_BOOST_SW [2] config
    option. The CPU_FREQ_BOOST_SW option is selected from it.

    Moreover the [2] depends on ARM_EXYNOS_CPUFREQ (which prevents from
    accidental enable/disable). And it selects automatically the
    EXYNOS_THERMAL, which is much better than depending only on THERMAL [3]
    (the generic framework).

    Depending only on [3], results at situation where SW BOOST can be
    enabled at x86 or ARM target with only generic THERMAL support (which
    doesn't protect from overheating).


    So the proposed solution:
    1. Defines global flag [1]
    2. This flag is selected only when dependencies for more HW close flag
    [2] are meet.
    3. It is more natural to have Kconfig BOOST enable/disable checkbox at
    platform cpufreq driver (with description closer to HW).
    4. Other ARCHs can easily define similar to [2] flag and by it select
    [1].

    For me the approach proposed in this patch is more natural and provides
    high protection level from accidental SW boost enable.

    --
    Best regards,

    Lukasz Majewski

    Samsung R&D Institute Poland (SRPOL) | Linux Platform Group


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