Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Fri, 10 Nov 2017 09:03:15 +0100 | Subject | Re: [PATCH v4 2/2] PM / QoS: Fix device resume latency framework |
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Hi Rafael,
On Tue, Nov 7, 2017 at 11:33 AM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > The special value of 0 for device resume latency PM QoS means > "no restriction", but there are two problems with that. > > First, device resume latency PM QoS requests with 0 as the > value are always put in front of requests with positive > values in the priority lists used internally by the PM QoS > framework, causing 0 to be chosen as an effective constraint > value. However, that 0 is then interpreted as "no restriction" > effectively overriding the other requests with specific > restrictions which is incorrect. > > Second, the users of device resume latency PM QoS have no > way to specify that *any* resume latency at all should be > avoided, which is an artificial limitation in general. > > To address these issues, modify device resume latency PM QoS to > use S32_MAX as the "no constraint" value and 0 as the "no > latency at all" one and rework its users (the cpuidle menu > governor, the genpd QoS governor and the runtime PM framework) > to follow these changes. > > Also add a special "n/a" value to the corresponding user space I/F > to allow user space to indicate that it cannot accept any resume > latencies at all for the given device. > > Fixes: 85dc0b8a4019 (PM / QoS: Make it possible to expose PM QoS latency constraints) > Link: https://bugzilla.kernel.org/show_bug.cgi?id=197323 > Reported-by: Reinette Chatre <reinette.chatre@intel.com> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Tested-by: Reinette Chatre <reinette.chatre@intel.com> > Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > > As noticed by Ramesh, the v3 had issues with an overlooked value > conversion and a stale comment, so here goes a v4.
JFTR, with v4, the WARN_ON() is no longer triggered when waking up r8a7740/armadillo or sh73a0/kzm9g by tapping the touchscreen.
I hadn't reported that before, as I only noticed it with v2 after you had already posted newer versions, so I wanted to try those first.
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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