Subject: Re: [PATCH v7 00/11] powerpc/powernv/cpuidle: Add support for POWER ISA v3 idle states

From: Michael Neuling <[email-masked]>
Date: Fri, 08 Jul 2016 12:49:08 +1000

Except for the issue with patch 7 I've already commented on the rest of
this series is good with me.  FWIW:

Acked-by: Michael Neuling <[email-masked]>

Thanks.

On Fri, 2016-07-08 at 02:17 +0530, Shreyas B. Prabhu wrote:
> POWER ISA v3 defines a new idle processor core mechanism. In summary,
>  a) new instruction named stop is added. This instruction replaces
> 	instructions like nap, sleep, rvwinkle.
>  b) new per thread SPR named PSSCR is added which controls the behavior
> 	of stop instruction. 
> 		
> PSSCR has following key fields
> 	Bits 0:3  - Power-Saving Level Status. This field indicates the
> 	lowest power-saving state the thread entered since stop
> 	instruction was last executed.
> 		
> 	Bit 42 - Enable State Loss                          
> 	0 - No state is lost irrespective of other fields  
> 	1 - Allows state loss
> 		
> 	Bits 44:47 - Power-Saving Level Limit      
> 	This limits the power-saving level that can be entered into.
> 		
> 	Bits 60:63 - Requested Level              
> 	Used to specify which power-saving level must be entered on
> 	executing stop instruction
> 		
> Stop idle states and their properties like name, latency, target
> residency, psscr value are exposed via device tree.
> 
> This patch series adds support for this new mechanism.
> 
> Patches 1-6 are cleanups and code movement.
> Patch 7 adds platform specific support for stop and psscr handling.
> Patch 8 and 9 are minor cleanup in cpuidle driver.
> Patch 10 adds cpuidle driver support.
> Patch 11 makes offlined cpu use deepest stop state.
> 
> Note: Documentation for the device tree bindings is posted here-
> http://patchwork.ozlabs.org/patch/629125/
> 
> Changes in v7
> =============
>  - File renamed to idle_book3s.S instead of idle_power_common.S
>  - Comment changes
>  - power_stop0, power_stop renamed to power9_idle and power_idle_stop
>  - PSSCR template is now a macro instead of storing in paca
>  - power9_idle in C file instead of assembly
>  - Fixed TOC related bug
>  - Handling subcore within FTR section
>  - Functions in idle.c reordered and broken into multiple functions
>  - calling __restore_cpu_power8/9 via cur_cpu_spec->cpu_restore 
>  - Added a minor patch with minor cleanups in cpuidle-powernv.c . This
>    was mainly to make the existing code consistent with the review
>    comments for new code
>  - Using stack for variables while probing for idle states instead of
>    kzalloc/kcalloc
> 
> Changes in v6
> =============
>  - Restore new POWER ISA v3 SPRS when waking up from deep idle
> 
> Changes in v5
> =============
>  - Use generic cpuidle constant CPUIDLE_NAME_LEN
>  - Fix return code handling for of_property_read_string_array
>  - Use DT flags to determine if are using stop instruction, instead of
>    cpu_has_feature
>  - Removed uncessary cast with names
>  - &stop_loop -> stop_loop
>  - Added POWERNV_THRESHOLD_LATENCY_NS to filter out idle states with high latency
> 
> Changes in v4
> =============
>  - Added a patch to use PNV_THREAD_WINKLE macro while requesting for winkle
>  - Moved power7_powersave_common rename to more appropriate patch
>  - renaming power7_enter_nap_mode to pnv_enter_arch207_idle_mode
>  - Added PSSCR layout to Patch 7's commit message
>  - Improved / Fixed comments
>  - Fixed whitespace error in paca.h
>  - Using MAX_POSSIBLE_STOP_STATE macro instead of hardcoding 0xF has
>    max possible stop state
> 
> Changes in v3
> =============
>  - Rebased on powerpc-next
>  - Dropping patch 1 since we are not adding a new file for P9 idle support
>  - Improved comments in multiple places
>  - Moved GET_PACA from power7_restore_hyp_resource to System Reset
>  - Instead of moving few functions from idle_power7 to idle_power_common,
>    renaming idle_power7.S to idle_power_common.S
>  - Moved HSTATE_HWTHREAD_STATE updation to power_powersave_common
>  - Dropped earlier patch 5 which moved few macros from idle_power_common to
>    asm/cpuidle.h. 
>  - Added a patch to rename reusable power7_* idle functions to pnv_*
>  - Added new patch that creates abstraction for saving SPRs before
>    entering deep idle states
>  - Instead of introducing new file idle_power_stop.S, P9 idle support
>    is added to idle_power_common.S using CPU_FTR sections.
>  - Fixed r4 reg clobbering in power_stop0
> 
> Changes in v2
> =============
>  - Rebased on v4.6-rc6
>  - Using CPU_FTR_ARCH_300 bit instead of CPU_FTR_STOP_INST
> 
> Cc: Rafael J. Wysocki <[email-masked]>
> Cc: Daniel Lezcano <[email-masked]>
> Cc: [email-masked]
> Cc: Benjamin Herrenschmidt <[email-masked]>
> Cc: Michael Ellerman <[email-masked]>
> Cc: Paul Mackerras <[email-masked]>
> Cc: Michael Neuling <[email-masked]>
> Cc: [email-masked]
> Cc: Rob Herring <[email-masked]>
> Cc: Lorenzo Pieralisi <[email-masked]>
> 
> Shreyas B. Prabhu (11):
>   powerpc/powernv: Use PNV_THREAD_WINKLE macro while requesting for
>     winkle
>   powerpc/kvm: make hypervisor state restore a function
>   powerpc/powernv: Rename idle_power7.S to idle_book3s.S
>   powerpc/powernv: Rename reusable idle functions to hardware agnostic
>     names
>   powerpc/powernv: Make pnv_powersave_common more generic
>   powerpc/powernv: abstraction for saving SPRs before entering deep idle
>     states
>   powerpc/powernv: Add platform support for stop instruction
>   cpuidle/powernv: Use CPUIDLE_STATE_MAX instead of
>     MAX_POWERNV_IDLE_STATES
>   cpuidle/powernv: cleanup powernv_add_idle_states
>   cpuidle/powernv: Add support for POWER ISA v3 idle states
>   powerpc/powernv: Use deepest stop state when cpu is offlined
> 
>  arch/powerpc/include/asm/cpuidle.h        |   2 +
>  arch/powerpc/include/asm/kvm_book3s_asm.h |   2 +-
>  arch/powerpc/include/asm/opal-api.h       |  11 +-
>  arch/powerpc/include/asm/ppc-opcode.h     |   4 +
>  arch/powerpc/include/asm/processor.h      |   2 +
>  arch/powerpc/include/asm/reg.h            |  10 +
>  arch/powerpc/kernel/Makefile              |   2 +-
>  arch/powerpc/kernel/exceptions-64s.S      |  30 +-
>  arch/powerpc/kernel/idle_book3s.S         | 664 ++++++++++++++++++++++++++++++
>  arch/powerpc/kernel/idle_power7.S         | 515 -----------------------
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S   |   4 +-
>  arch/powerpc/platforms/powernv/idle.c     | 185 +++++++--
>  arch/powerpc/platforms/powernv/powernv.h  |   1 +
>  arch/powerpc/platforms/powernv/smp.c      |   4 +-
>  drivers/cpuidle/cpuidle-powernv.c         |  99 ++++-
>  15 files changed, 940 insertions(+), 595 deletions(-)
>  create mode 100644 arch/powerpc/kernel/idle_book3s.S
>  delete mode 100644 arch/powerpc/kernel/idle_power7.S
>