Hi Rob, On Mon, May 2, 2016 at 1:56 PM, Rob Herring <robh@xxxxxxxxxx> wrote: > On Wed, Apr 20, 2016 at 12:31:22PM +0100, Will Deacon wrote: >> On Mon, Apr 18, 2016 at 01:04:53PM -0700, Tai Tri Nguyen wrote: >> > >> +Required properties for MCB subnode: >> > >> +- compatible : Shall be "apm,xgene-pmu-mcb". >> > >> +- reg : First resource shall be the MCB PMU resource. >> > >> +- index : Instance number of the MCB PMU. >> > >> + >> > >> +Required properties for MC subnode: >> > >> +- compatible : Shall be "apm,xgene-pmu-mc". >> > >> +- reg : First resource shall be the MC PMU resource. >> > >> +- index : Instance number of the MC PMU. >> > > >> > > Don't use indexes. You probably need phandles to the nodes these are >> > > related to. >> > > >> > > How many variations of child nodes do you expect to have? 2, 10, 50? You >> > > might want to just collapse all this down to a single node and put this >> > > information in the driver if it is fixed for each SoC and there's only a >> > > handful. >> > > >> > >> > For each kind of PMU, for example memory controller PMU, I expect to >> > have the number of instances up to 8. >> > They are actually all independent PMU nodes and have their own CSR memory bases. >> > The indexes are used for exposing the devices to perf user only. It >> > doesn't have an impact on the programming model. >> > Mark also had the same concern. >> >> Regardless, I'll need an ack from Rob or Mark before I can merge this. > > I still have a concern with this. Needing an index to expose to the user > is generally not a valid reason. That's OS specific and therefore > doesn't belong in DT. > > Rob I can use device name here. However, the perf event names will be different between DT and ACPI which I want to avoid. And the names don't look good at all. Also, specifically for MC and MCB PMUs, the indexes are compared against the active MC/MCB mask to find out whether they are populated or not. Without using the index property, I will also need a mapping function of physical device addresses and their physical ids. Thanks, -- Tai -- 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
