From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com> Hi,
In the current implementation, the code for ISA v3.0 stop implementation has a couple of shortcomings. a) The code hand-codes the values for ESL,EC,TR,MTL bits of PSSCR and uses only the RL field from the firmware. While this is not incorrect, since the hand-coded values are legitimate, it is not a very flexible design since the firmware has the capability to communicate these values via the "ibm,cpu-idle-state-psscr" and "ibm,cpu-idle-state-psscr-mask" properties. In case where the firmware provides values for these fields that is different from the hand-coded values, the current code will not work as intended. b) Due to issue a), the current code assumes that ESL=EC=1 for all the stop states and hence the wakeup from the stop instruction will happen at 0x100, the system-reset vector. However, the ISA v3.0 allows the ESL=EC=0 behaviour where the corresponding stop-state loses no state and wakes up from the subsequent instruction. The current code doesn't handle this case. This patch series addresses these issues. The first patch in the series renames the existing IDLE_STATE_ENTER_SEQ macro to IDLE_STATE_ENTER_SEQ_NORET. It reuses the name IDLE_STATE_ENTER_SEQ for entering into stop-states which wake up at the subsequent instruction. The second patch in the series fixes issues a) and b) by ensuring that the psscr-value and the psscr-mask provided by the firmware are what will be used to set a particular stop state. It also adds support for handling wake-up from stop states which were entered with ESL=EC=0. These patches depend on the following skiboot patch that exports the PSSCR values and the mask for all the stop states: https://lists.ozlabs.org/pipermail/skiboot/2016-September/004869.html Gautham R. Shenoy (2): powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro powernv: Pass PSSCR value and mask to power9_idle_stop arch/powerpc/include/asm/cpuidle.h | 5 ++- arch/powerpc/include/asm/processor.h | 3 +- arch/powerpc/kernel/exceptions-64s.S | 6 +-- arch/powerpc/kernel/idle_book3s.S | 41 ++++++++++------- arch/powerpc/platforms/powernv/idle.c | 76 +++++++++++++++++++++++++++----- arch/powerpc/platforms/powernv/powernv.h | 3 +- arch/powerpc/platforms/powernv/smp.c | 7 +-- drivers/cpuidle/cpuidle-powernv.c | 30 ++++++++++--- 8 files changed, 127 insertions(+), 44 deletions(-) -- 1.9.4
