[Intel-gfx] [PATCH 1/2] tests/pm_rps: Round requested freq correctly

[Jeff McGee]

On Fri, Feb 07, 2014 at 11:15:15AM +0100, Daniel Vetter wrote:
> On Fri, Feb 7, 2014 at 10:33 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > On Fri, Feb 07, 2014 at 10:03:33AM +0100, Daniel Vetter wrote:
> >> The kernel will round it, so if we don't we'll have a spurious
> >> mismatch. Happens on my machine here with 650-1300MHz range, where the
> >> midpoint is 975.
> >>
> >> Cc: Jeff McGee <jeff.mcgee at intel.com>
> >> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> >> ---
> >>  tests/pm_rps.c | 3 +++
> >>  1 file changed, 3 insertions(+)
> >>
> >> diff --git a/tests/pm_rps.c b/tests/pm_rps.c
> >> index 467038104ec6..27e758755e3f 100644
> >> --- a/tests/pm_rps.c
> >> +++ b/tests/pm_rps.c
> >> @@ -350,6 +350,9 @@ static void min_max_config(void (*check)(void))
> >>  {
> >>       int fmid = (origfreqs[RPn] + origfreqs[RP0]) / 2;
> >>
> >> +     /* hw (and so kernel) currently rounds to 50 MHz ... */
> >
> > s/rounds/truncates/ or if it really does round, you need to adjust the
> > calculation.
> 
> We just need to use something divisible by 50 so that the value we
> write and the one we get match up. Whether it's truncating or rounding
> doesn't matter really.
> -Daniel

Darn, I considered this possibility but forgot to account for it in the test.
I think what I was going to do was to create another writeval variant
which doesn't do read back matching check. This was because I didn't want to
assume that all systems use a 50 Mhz frequency increment (do they all?).
-Jeff