On Mon, Dec 14, 2015 at 02:30:53PM +0100, Linus Walleij wrote: > On Thu, Dec 10, 2015 at 3:32 PM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > > On Thu, Dec 10, 2015 at 03:14:15PM +0100, Linus Walleij wrote: > >> diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt > >> index d181b7c4c522..aae7387acbdb 100644 > >> --- a/Documentation/devicetree/bindings/arm/l2cc.txt > >> +++ b/Documentation/devicetree/bindings/arm/l2cc.txt > >> @@ -75,6 +75,7 @@ Optional properties: > >> specified to indicate that such transforms are precluded. > >> - arm,parity-enable : enable parity checking on the L2 cache (L220 or PL310). > >> - arm,parity-disable : disable parity checking on the L2 cache (L220 or PL310). > >> +- arm,outer-sync-disable : disable the outer sync operation on the L2 cache. > > > > I'm not sure what this means from a HW perspective. The "outer sync" > > operation is Linux terminology and doesn't show up in the TRM for L220. > > > > What is the (integration? HW?) bug that we're trying to avoid the effect > > of? It sounds like we should be describing that. > > > > We should at least have a better definition of what this means we must > > avoid. > > So this code is a bit ancient, and we're trying to migrate it to device tree. > > It was inspired by this board file patch from Arnd: > http://marc.info/?l=linux-arm-kernel&m=144846938616893&w=2 > > Then I go back and dig in the code and I find this: > > commit 2503a5ecd86c002506001eba432c524ea009fe7f > Author: Catalin Marinas <catalin.marinas@xxxxxxx> > Date: Thu Jul 1 13:21:47 2010 +0100 > > ARM: 6201/1: RealView: Do not use outer_sync() on ARM11MPCore > boards with L220 > > RealView boards with certain revisions of the L220 cache controller (ARM11* > processors only) may have issues (hardware deadlock) with the > recent changes to > the mb() barrier implementation (DSB followed by an L2 cache > sync). The patch > redefines the RealView ARM11MPCore mandatory barriers without the > outer_sync() > call. > > Cc: <stable@xxxxxxxxxx> > Tested-by: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx> > Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > > And that is as much as it says. > > It is working around a hardware lockup in some core tiles. Is it > enough if I add this > to the explanation or do we need to send Catalin or Will down in the archives > to read netlists? ;) /me delegates to Rutland. Mark -- still want a better definition? ;) 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
