From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@kernel.org (Kevin Hilman) Date: Thu, 13 Aug 2015 20:40:42 -0700 Subject: [PATCH 2/9] PM / Domains: Remove dev->driver check for runtime PM In-Reply-To: (Geert Uytterhoeven's message of "Thu, 13 Aug 2015 10:57:38 +0200") References: <1438731339-58317-1-git-send-email-lina.iyer@linaro.org> <1438731339-58317-3-git-send-email-lina.iyer@linaro.org> <7hfv3onv5c.fsf@deeprootsystems.com> Message-ID: <7hwpwylepx.fsf@deeprootsystems.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Geert Uytterhoeven writes: > Hi Kevin, > > On Wed, Aug 12, 2015 at 9:50 PM, Kevin Hilman wrote: >> Lina Iyer writes: >> >>> Remove check for driver of a device, for runtime PM. Device may be >>> suspended without an explicit driver. This check seems to be vestigial >>> and incorrect in the current context. >> >> This one should probably have been RFC. >> >> For a little more context here, this was uncovered when experimenting >> with using runtime PM for CPU devices which don't have a dev->driver. >> >> This check might have made sense before PM domains, but with PM domains, >> it's entirely possible to have a simple device without a driver and the >> PM domain handles all the necesary PM, so I think this check >> could/should be removed. >> >> Thoughts? > > Simple devices without a driver aren't handled automatically. > At minimum, the driver should call pm_runtime_enable(), cfr. > drivers/bus/simple-pm-bus.c. That's correct, and in the proof-of-concept stuff I hacked up and in Lina's series, the CPU "devices" do indeed to this. Without that, they wouldn't end up ever taking this codepath through genpd's runtime_suspend and power_off hooks. Also, I'm not sure if your comment was meant to be an objection to the patch? or if you're OK with it. Thanks for the feedback, Kevin