On Fri, Mar 14, 2014 at 07:14:37AM +0000, Chanwoo Choi wrote: > Hi Mark, > > On 03/14/2014 02:53 AM, Mark Rutland wrote: > > On Thu, Mar 13, 2014 at 08:17:29AM +0000, Chanwoo Choi wrote: > >> This patch add busfreq driver for Exynos4210/Exynos4x12 memory interface > >> and bus to support DVFS(Dynamic Voltage Frequency Scaling) according to PPMU > >> counters. PPMU (Performance Profiling Monitorings Units) of Exynos4 SoC provides > >> PPMU counters for DMC(Dynamic Memory Controller) to check memory bus utilization > >> and then busfreq driver adjusts dynamically the operating frequency/voltage > >> by using DEVFREQ Subsystem. > >> > >> Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> > >> --- > >> .../devicetree/bindings/devfreq/exynos4_bus.txt | 49 ++++++++++++++++++++++ > >> 1 file changed, 49 insertions(+) > >> create mode 100644 Documentation/devicetree/bindings/devfreq/exynos4_bus.txt > >> > >> diff --git a/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt b/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt > >> new file mode 100644 > >> index 0000000..2a83fcc > >> --- /dev/null > >> +++ b/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt > >> @@ -0,0 +1,49 @@ > >> + > >> +Exynos4210/4x12 busfreq driver > >> +----------------------------- > >> + > >> +Exynos4210/4x12 Soc busfreq driver with devfreq for Memory bus frequency/voltage > >> +scaling according to PPMU counters of memory controllers > >> + > >> +Required properties: > >> +- compatible : should contain Exynos4 SoC type as follwoing: > >> + - "samsung,exynos4x12-busfreq" for Exynos4x12 > >> + - "samsung,exynos4210-busfreq" for Exynos4210 > > > > Is there a device called "busfreq"? What device does this binding > > describe? > > I'll add detailed description of busfreq as following: > > "busfreq(bus frequendcy)" driver means that busfreq driver control dynamically > memory bus frequency/voltage by checking memory bus utilization to optimize > power-consumption. When checking memeory bus utilization, exynos4_busfreq driver > would use PPMU(Performance Profiling Monitoring Units). This still sounds like a description of the _driver_, not the _device_. The binding should describe the hardware, now the high level abstraction that software is going to build atop of it. It sounds like this is a binding for the DMC PPMU? Is the PPMU a component of the DMC, or is it bolted on the side? > > > > > >> +- reg : offset and length of the ppmudmc0/1 > >> + - PPMU (Performance Profiling Monitoring Units) > > > > You seem to require a particular order here. It would be good to be > > explicit about it. > > OK, I'll modify it as following: > the offset and length of the PPMU_DMC0 / PPMU_DMC1 > PPMU_DMC0/PPMU_DMC1 show memory buy utilization to exynos4_bus driver. > > > > >> + : It is to profile performance event of DMC(Dynamic Memory > >> + Controller) So, exynos4_bus.c can check memory bus utilization > >> + by using PPMU of Exynos4 SoC. > > > > This is superfluous, and Linux-specific. The binding document shouldn't > > need to refer to drivers. > > I'll remove this description. > > > > >> +- clocks : clock number of ppmudmc0/1 > >> +- clock-names : clock name of ppmudmc0/1 > > > > Are these two clocks, or one clock with a slash in the name? > > > > Please list each name separately. > > I'll expalin clocks as following: > "ppmudmc0", "ppmudmc1" > > > > >> +- vdd_int-supply: regulator for interface block of Exynos4 How does the interface block relate to the DMC / PPMU? Cheers, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
