On Wed, Apr 23, 2014 at 11:31:09AM +0100, Neil Zhang wrote: > > > -----Original Message----- > > From: Will Deacon [mailto:will.deacon@xxxxxxx] > > Sent: 2014年4月22日 18:37 > > To: Neil Zhang > > Cc: linux@xxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > > linux-kernel@xxxxxxxxxxxxxxx; Sudeep Holla; devicetree@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH v4] ARM: perf: save/restore pmu registers in pm notifier > > > > Hi Neil, > > > > On Tue, Apr 22, 2014 at 03:26:36AM +0100, Neil Zhang wrote: > > > This adds core support for saving and restoring CPU PMU registers for > > > suspend/resume support i.e. deeper C-states in cpuidle terms. > > > This patch adds support only to ARMv7 PMU registers save/restore. > > > It needs to be extended to xscale and ARMv6 if needed. > > > > > > I made this patch because DS-5 is not working on Marvell's CA7 based SoCs. > > > And it has consulted Sudeep KarkadaNagesha's patch set for multiple PMUs. > > > > > > Thanks Will and Sudeep's suggestion to only save / restore used events. > > > > Whilst this is a step in the right direction, I'd still like to see the save/restore > > predicated on something in the device-tree or otherwise. Most SoCs *don't* > > require these registers to be preserved by software, so we need a way to > > describe that the PMU is in a power-domain where its state is lost when the > > CPU goes idle. > > > > This doesn't sound like a PMU-specific problem, so there's a possibility that > > this has been discussed elsewhere, in the context of other IP blocks > > > > [adding the devicetree list in case somebody there is aware of any work in > > this area] > > > > Thanks Will. > What should I do now? > Add a filed under PMU or waiting for somebody whether there are general > supporting for power domain maintain. I think we need some input from the device-tree guys to see whether they would object to us solving this locally (in the PMU node) or not. Personally, I'd much prefer a general way to describe the need for pm-notifiers, but if that's not being looked at then we can cook something specifically for our needs. Will -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
