From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Thu, 28 Apr 2016 14:57:27 +0100 Subject: [PATCH v2 2/2] Documentation: devicetree: Add PL310 PM bindings In-Reply-To: References: <1456265019-23900-1-git-send-email-brad.mouring@ni.com> <1461015411-14000-1-git-send-email-brad.mouring@ni.com> <1461015411-14000-3-git-send-email-brad.mouring@ni.com> <20160419224122.GE19428@n2100.arm.linux.org.uk> <20160427085947.GG19428@n2100.arm.linux.org.uk> Message-ID: <20160428135727.GH19428@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Apr 27, 2016 at 07:48:18AM -0500, Rob Herring wrote: > On Wed, Apr 27, 2016 at 3:59 AM, Russell King - ARM Linux > wrote: > > On Wed, Apr 20, 2016 at 09:04:39AM -0500, Rob Herring wrote: > >> On Tue, Apr 19, 2016 at 5:41 PM, Russell King - ARM Linux > >> wrote: > >> > On Tue, Apr 19, 2016 at 04:38:14PM -0500, Rob Herring wrote: > >> >> On Mon, Apr 18, 2016 at 4:36 PM, Brad Mouring wrote: > >> >> > Document the DT bindings for controlling ARM PL310 Power Control > >> >> > settings. > >> >> > > >> >> > Signed-off-by: Brad Mouring > >> >> > >> >> What happened to Josh's ack? > >> >> > >> >> > --- > >> >> > Documentation/devicetree/bindings/arm/l2c2x0.txt | 4 ++++ > >> >> > 1 file changed, 4 insertions(+) > >> >> > > >> >> > diff --git a/Documentation/devicetree/bindings/arm/l2c2x0.txt b/Documentation/devicetree/bindings/arm/l2c2x0.txt > >> >> > index fe0398c..c1c756e 100644 > >> >> > --- a/Documentation/devicetree/bindings/arm/l2c2x0.txt > >> >> > +++ b/Documentation/devicetree/bindings/arm/l2c2x0.txt > >> >> > @@ -84,6 +84,10 @@ Optional properties: > >> >> > - prefetch-instr : Instruction prefetch. Value: <0> (forcibly disable), > >> >> > <1> (forcibly enable), property absent (retain settings set by > >> >> > firmware) > >> >> > +- arm,dynamic-clock-gating : L2 dynamic clock gating. Value: <0> (forcibly > >> >> > + disable), <1> or property absent (forcibly enable) > >> >> > +- arm,standby-mode: L2 standby mode enable. Value <0> (forcibly disable), > >> >> > + <1> or property absent (forcibly enable) > >> >> > >> >> What happened to "retain settings set by firmware"? > >> > > >> > I said we shouldn't. Current behaviour is that we enable these features, > >> > and moving to missing-means-retain means that everything today ends up > >> > with these features disabled. IOW, it's yet another change of actual > >> > behaviour that every platform would see. > >> > >> Right, but then the properties are different from prefetch-instr and > >> others IIRC. We're letting the OS define the binding. If BSD doesn't > >> enable these settings currently, then there is a mismatch between the > >> binding and actual behavior. Saying "retain firmware settings" also > >> defines specific OS behavior. I think absent should mean OS is free to > >> do whatever it wants which could be retain firmware settings, enable > >> or disable. In other words, it is undefined as this ship has already > >> sailed. > > > > I agree with "the ship has already sailed" but I disagree with the > > rest of your comment. The ship has already sailed in that we have > > an established behaviour which has been there for 18 months. Given > > the time period, it's not something I'm going to change at this > > stage, sorry. > > > > Why? Such a change will go unnoticed, and it's particularly hard > > to debug why battery life has reduced. > > > > I guess we need to find a way to ensure that the default behaviour > > stays. Whether that's by _everyone_ updating their DT files with > > the new properties or some other way, I don't care. I only care > > that we retain the behaviour we've had for the last 18 months. > > I'm not suggesting that we change behavior at all. I'm only suggesting > that we leave it undefined in the binding documentation because the > behavior is possibly OS specific and can't really be defined there. Ok. -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.