On 10/11/16 18:54, Gautham R. Shenoy wrote: > From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com> > > This is the third iteration of the patchset to use the psscr_val and > psscr_mask provided by the firmware for each of the stop states. > > The previous version can be found here: > > [v2]: https://lkml.org/lkml/2016/10/27/143 > [v1]: https://lkml.org/lkml/2016/9/29/45 > > This version fixes a couple of bugs pertaining to strncpy and > initialization of the target-residency values of nap and sleep > which were pointed out by Paul and Oliver in the earlier version. > > Synopsis > ========== > 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. >
Sounds reasonable Balbir Singh.
