On Tuesday, September 07, 2010, mark gross wrote: > On Thu, Sep 02, 2010 at 10:09:20PM +0200, Rafael J. Wysocki wrote: > > On Thursday, September 02, 2010, mark gross wrote: > > > On Fri, Aug 27, 2010 at 07:31:46AM -0700, Kevin Hilman wrote: > > > > Saravana Kannan <skannan@xxxxxxxxxxxxxx> writes: > > > > > > > > > Some drivers/devices might need some minimum system bus performance to > > > > > provide acceptable service. Provide a PM QoS parameter to send these requests > > > > > to. > > > > > > > > > > The new parameter is named "system bus performance" since it is generic enough > > > > > for the unit of the request to be frequency, bandwidth or something else that > > > > > might be appropriate. It's up to each implementation of the QoS provider to > > > > > define what the unit of the request would be. > > > > > > > > > > Signed-off-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx> > > > > > > > > With this current design, only one system-wide bus would be managed. > > > > What if a platform has more than one independently scalable bus? > > > > > > > > I think the only scalable way to handle this kind of thing is to have > > > > per-device QoS constraints that can then be combined/aggregated by parent > > > > devices/busses. > > > > > > > > At LPC this year, I've proposed per-device QoS constraints[1] as a topic > > > > for the PM mini-conf. I hope some folks from the MSM camp can be there > > > > for these discussions. > > > > > > > > Kevin > > > > > > > > [1] http://www.linuxplumbersconf.org/2010/ocw/proposals/819 > > > > > > I thought a pm_qos like thing per bus would be a patch or you where > > > going to put up to the driver model. ;) > > > > > > The current pm_qos would stick around for higher level pm_qos things. > > > So making the system bus and changing to a summation aggregation would > > > be temporary thing. > > > > > > Or are you you saying we shouldn't put system_bus into pm_qos at all and > > > instead we should put effort into adding it to the driver model for > > > buses? > > > > Hmm, well, what's system_bus? > > > > Rafael > > My understanding is that system_bus is a somewhat generic concept that > has meaning only in platform specific hardware configurations pm_qos > request class for device specific buses. Memory, SDIO, SPI, i2c etc. > > I'm not sure if it should be exposed up to user mode as an ABI. Its > pretty abstract and its meaning is perhaps a bit mutable across target > architectures at this time. No, it shouldn't. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
