[PATCH 0/6] cpufreq: use generic cpufreq drivers for Exynos4210 platform

[Bartlomiej Zolnierkiewicz]

Hi,

This patch series removes the use of Exynos4210 specific support
from cpufreq-exynos driver and enables the use of cpufreq-dt driver
for this platform.

It consists of a modified "[PATCH v12 0/6] cpufreq: use generic
cpufreq drivers for exynos platforms" [1] patch series from Thomas
Abraham.  As there have not been updates of this patchset since
November 2014 I decided to dust it off myself.  I updated Thomas'
patchset to current kernels, fixed bugs that I noticed and removed
non-Exynos4210 support for now (to speed up inclusion in upstream
kernel).  Since some modifications were not trivial I dropped all
Reviewed-by:, Tested-by: and Acked-by: tags.  Please review/test
this patchset and reply with revelant tag (Thank You!).  I also
plan to work on Exynos4x12 support next (which was missing in
the original patchset) and then on Exynos5250/Exynos5420 one.

This patch series has been tested on Exynos4210 based Origen and
Trats boards.

Depends on:
- next-20150330 branch of linux-next kernel tree
  (mfd tree contains a crucial fix for MAX8997 PMIC support)
- "[PATCH] clk: samsung: exynos4: Disable ARMCLK down feature on
  Exynos4210 SoC" [2]

[1] https://www.marc.info/?l=linux-arm-kernel&m=141657611003803&w=2
[2] https://lkml.org/lkml/2015/3/27/568

Changes over Thomas' code:
- fixed issue with wrong dividers being setup by Common Clock Framework
  (by an addition of CLK_RECALC_NEW_RATES clock flag to mout_apll clock,
  without this change cpufreq-dt driver showed ~10 mA larger energy
  consumption when compared to cpufreq-exynos one when "performance"
  cpufreq governor was used on Exynos4210 SoC based Origen board), this
  was probably meant to be workarounded by use of CLK_GET_RATE_NOCACHE
  and CLK_DIVIDER_READ_ONLY clock flags in the original patchset (in
  "[PATCH v12 6/6] clk: samsung: remove unused clock aliases and update
  clock flags") but using these flags is not sufficient to fix the issue
  observed
- fixed issue with setting lower dividers before the parent clock speed
  was lowered (the issue resulted in lockup on Exynos4210 SoC based
  Origen board when "ondemand" cpufreq governor was stress tested)
- fixed missing spin_unlock on error in exynos_cpuclk_post_rate_change()
  problem by moving cfg_data search outside of the spin locked area
- removed leftover kfree() in exynos_register_cpu_clock() that could
  result in dereferencing the NULL pointer on error
- moved spin_lock earlier in exynos_cpuclk_pre_rate_change() to cover
  reading of E4210_SRC_CPU and E4210_DIV_CPU1 registers
- added missing "last chance" checks to wait_until_divider_stable() and
  wait_until_mux_stable() (needed in case that IRQ handling took long
  time to proceed and resulted in function printing incorrect error
  message about timeout)
- moved E4210_CPU_DIV[0,1]() macros just before their only users,
  this resulted in moving them from patch #2 to patch #3/6 ("clk:
  samsung: exynos4: add cpu clock configuration data and instantiate
  cpu clock")
- added my Copyrights to drivers/clk/samsung/clk-cpu.c
- updated exynos-cpufreq.[c,h]
- removed non-Exynos4210 support for now
- dropped "[PATCH v12 6/6] clk: samsung: remove unused clock aliases and
  update clock flags" altogether for now

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics


Bartlomiej Zolnierkiewicz (1):
  clk: add CLK_RECALC_NEW_RATES clock flag for Exynos cpu clock support

Thomas Abraham (5):
  clk: samsung: add infrastructure to register cpu clocks
  clk: samsung: exynos4: add cpu clock configuration data and
    instantiate cpu clock
  ARM: dts: Exynos4210: add CPU OPP and regulator supply property
  ARM: Exynos: switch to using generic cpufreq driver for Exynos4210
  cpufreq: exynos: remove Exynos4210 specific cpufreq driver support

 arch/arm/boot/dts/exynos4210-origen.dts         |    4 +
 arch/arm/boot/dts/exynos4210-trats.dts          |    4 +
 arch/arm/boot/dts/exynos4210-universal_c210.dts |    4 +
 arch/arm/boot/dts/exynos4210.dtsi               |   12 +
 arch/arm/mach-exynos/exynos.c                   |   21 +-
 drivers/clk/clk.c                               |    3 +
 drivers/clk/samsung/Makefile                    |    2 +-
 drivers/clk/samsung/clk-cpu.c                   |  349 +++++++++++++++++++++++
 drivers/clk/samsung/clk-cpu.h                   |   73 +++++
 drivers/clk/samsung/clk-exynos4.c               |   24 +-
 drivers/cpufreq/Kconfig.arm                     |   11 -
 drivers/cpufreq/Makefile                        |    1 -
 drivers/cpufreq/exynos-cpufreq.c                |    5 +-
 drivers/cpufreq/exynos-cpufreq.h                |    9 -
 drivers/cpufreq/exynos4210-cpufreq.c            |  184 ------------
 include/linux/clk-provider.h                    |    1 +
 16 files changed, 495 insertions(+), 212 deletions(-)
 create mode 100644 drivers/clk/samsung/clk-cpu.c
 create mode 100644 drivers/clk/samsung/clk-cpu.h
 delete mode 100644 drivers/cpufreq/exynos4210-cpufreq.c

-- 
1.7.9.5