Hi Rob, On 3/28/19 17:12, Rob Herring wrote: > On Wed, Mar 13, 2019 at 11:00:07AM +0200, Georgi Djakov wrote: >> In addition to frequency and voltage, some devices may have bandwidth >> requirements for their interconnect throughput - for example a CPU >> or GPU may also need to increase or decrease their bandwidth to DDR >> memory based on the current operating performance point. >> >> Extend the OPP tables with additional property to describe the bandwidth >> needs of a device. The average and peak bandwidth values depend on the >> hardware and its properties. > > How would this work if you have 1 OPP (for the bus/interconnect/ddr) and > 2 devices with variable bandwidth needs? Or 'device' here means the > interconnect? This is a property of the consumer devices and not of the bus. It's fine for devices to have different bandwidth needs and to be connected to a shared bus. In this case the framework knows the topology and can determine which parts of the bus are shared and aggregate the traffic accordingly. >> >> Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx> >> --- >> Documentation/devicetree/bindings/opp/opp.txt | 45 +++++++++++++++++++ >> 1 file changed, 45 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt >> index 76b6c79604a5..fa598264615f 100644 >> --- a/Documentation/devicetree/bindings/opp/opp.txt >> +++ b/Documentation/devicetree/bindings/opp/opp.txt >> @@ -129,6 +129,9 @@ Optional properties: >> - opp-microamp-<name>: Named opp-microamp property. Similar to >> opp-microvolt-<name> property, but for microamp instead. >> >> +- opp-bw-MBs: The interconnect bandwidth is specified with an array containing >> + the two integer values for average and peak bandwidth in megabytes per second. > > -MBps would be better IMO. Either way, units should be documented in > property-units.txt. Agree! Of course! Thanks, Georgi
