On Fri, Dec 8, 2017 at 12:47 PM, Michael Ellerman <[email protected]> wrote: > "Rafael J. Wysocki" <[email protected]> writes: > >> On Thu, Dec 7, 2017 at 6:59 AM, Gautham R. Shenoy >> <[email protected]> wrote: >>> From: "Gautham R. Shenoy" <[email protected]> >>> >>> On POWERNV platform, Pstates are 8-bit values. On POWER8 they are >>> negatively numbered while on POWER9 they are positively >>> numbered. Thus, on POWER9, the maximum number of pstates could be as >>> high as 256. >>> >>> The current code interprets pstates as a signed 8-bit value. This >>> causes a problem on POWER9 platforms which have more than 128 pstates. >>> On such systems, on a CPU that is in a lower pstate whose number is >>> greater than 128, querying the current pstate returns a "pstate X is >>> out of bound" error message and the current pstate is reported as the >>> nominal pstate. >>> >>> This patch fixes the aforementioned issue by correctly differentiating >>> the sign whenever a pstate value read, depending on whether the >>> pstates are positively numbered or negatively numbered. >>> >>> Fixes: commit 09ca4c9b5958 ("cpufreq: powernv: Replacing pstate_id with >>> frequency table index") >>> Cc: <[email protected]> #v4.8 >>> Signed-off-by: Gautham R. Shenoy <[email protected]> >>> Tested-and-reviewed-by: Shilpasri G Bhat <[email protected]> >>> Acked-by: Viresh Kumar <[email protected]> >> >> I'm going to apply this, or please let me know if you want to route it >> differently. > > Do you mind waiting for now, we're still debating how to fix it.
No problem. :-) Just please let me know when you're ready.
