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SubjectRe: [PATCH 4/4] cpufreq: arm_big_little: add SCPI interface driver
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On Mon, 2015-04-27 at 12:40 +0100, Sudeep Holla wrote:
> On some ARM based systems, a separate Cortex-M based System Control
> Processor(SCP) provides the overall power, clock, reset and system
> control including CPU DVFS. SCPI Message Protocol is used to
> communicate with the SCPI.
>
> This patch adds a interface driver for adding OPPs and registering
> the arm_big_little cpufreq driver for such systems.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: linux-pm@vger.kernel.org
> ---
> drivers/cpufreq/Kconfig.arm | 9 ++++
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/scpi-cpufreq.c | 103 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 113 insertions(+)
> create mode 100644 drivers/cpufreq/scpi-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 4f3dbc8cf729..9e678bf1687c 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -24,6 +24,15 @@ config ARM_VEXPRESS_SPC_CPUFREQ
> This add the CPUfreq driver support for Versatile Express
> big.LITTLE platforms using SPC for power management.
>
> +config ARM_SCPI_CPUFREQ
> + tristate "SCPI based CPUfreq driver"
> + depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL

And ARM_BIG_LITTLE_CPUFREQ depends on CONFIG_ARM, so we can't build this
for arm64, which is the only platform (Juno) we have to run these
patches on. Unless you're prepared for a horrid hack...
https://github.com/ARM-software/linux/commit/b9ceaa0cbd7c57d57ee7e69146cc627697570f6e
or a pair of less horrid ones...
http://git.linaro.org/kernel/linux-linaro-tracking.git/commit/4b5dd8ff98613b7e90c8f3214522a00ab6900fe9
http://git.linaro.org/kernel/linux-linaro-tracking.git/commit/8641dbfe253f6a9061742ca11f769fc1d82c2aaa

Any reason why the above two aren't suitable for mainline Linux? The
second was actually committed then reverted because it broke arm64
builds, but the other patch fixes that.

--
Tixy



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