>>-----Original Message----- >>From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of >>Gadiyar, Anand >>Sent: Friday, June 04, 2010 8:32 AM >>To: Kevin Hilman; Mike Chan >>Cc: linux-omap@xxxxxxxxxxxxxxx; Paul Walmsley >>Subject: RE: Future of resource framework? >> >>Kevin Hilman wrote: >>> Mike Chan <mike@xxxxxxxxxxx> writes: >>> >>> > On Fri, May 21, 2010 at 9:47 AM, Kevin Hilman >>> > <khilman@xxxxxxxxxxxxxxxxxxx> wrote: >>> >> Mike Chan <mike@xxxxxxxxxxx> writes: >>> >> >>> >>> I'm not sure if this has been discussed, yet but since it seems that >>> >>> the resource framework will not be making it upstream, I am curious >>> >>> what are the replacements under consideration. I am starting to see >>> >>> similar issues on other platforms (msm / tegra) so more generic >>> >>> (non-omap) solution might be something to consider. >>> >> >>> >> Hi Mike, >>> >> >>> >> Which parts of the SRF do you currently use and find useful? It would >>> >> be helpful for us to to understand the parts you see as useful and >>> >> potentially helpful to generalize. >>> >> >>> > >>> > Off the top of my head, for Droid specifically, OPP values are useful, >>> > although in theory if you changed OPP requests to cpu throughput that >>> > might give the equivalent functionality. >>> > >>> > Memory bus speeds / bandwidth, although its tied to CPU, which >>> > ultimately ends up in a cpu speed bump. >>> > >>> > Although most of the usage I've seen are just hacks, ie: the driver >>> > knows it needs 550mhz from the cpu so it will request some bogus >>> > value. >>> > >>> > >>> >> As you know, the current implementation has a several layers >>> >> and attempts to manage several things: OPPs, latencies etc. >>> >> >>> >> Our current plans are essentially to break up the "one framework to >>> >> rule them all" philosophy and design of SRF and manage the various >>> >> pieces by exending other layers such as the new OPP layer and voltage >>> >> layers. Latencies are being managed by the omap_device layer and we >>> >> will hopefully have some discussions with the broader linux-pm >>> >> community about generalizing that more into the generic driver model >>> >> over this year. >>> >> >>> > >>> > Bus speed is a common resource I see for omap / msm / tegra. Clocks >>> > for devices also. >>> > >>> > ie: If I'm doing heavy mem operation and need max memory bus, I might >>> > need to request higher performance. (which might mean 600mhz on >>> > omap34030, on msm it might mean AXI clock running at 128mhz, and >>> > something else on tegra). >>> > >>> > Or if I'm doing graphics, I may need to up the gfx clock rate, or >>> > swich which pll its sourcing etc.. etc.. >>> > >>> > It doesn't look like pm qos has bus support, or even clock support, >>> > and this gets tricky if you want something semi-general. >>> >>> What we're hoping to work towards (and has come up in the suspend >>> blocker related discussions) is moving towards a way to track >>> per-device (or per-subsystem) constraints like latency and throughput >>> in real world terms (usecs, bytes/sec, etc.) that would be general >>> way. >>> >>> These constraints would then be visible to the bus- or >>> platform-specific code that could make intelligent decisions with them >>> (i.e whether or not to raise/lower OPP or bus speed, or whether or not >>> to power down a powerdomain etc.) >>> >> >> >>What if a driver knows that it cannot afford to let the PM layer >>turn off the power domain at certain points of time (maybe as long >>as a USB cable is connected). How can this be specified in terms >>of a latency or throughput constraint? >> >>Just curious, since I don't understand current OMAP3 PM code >>as well as I would like to. Latency should internally map to a power domain state for the power domain associated with the device. And the SRF/new replacement fmwk should take care of taking requests from all devices associated with a power domain and programming the power domain to hit the accepted low power state. Regards Thara -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
