On Wed, Aug 24, 2016 at 04:53:35PM +0800, Peter Chen wrote: > On Tue, Aug 23, 2016 at 04:02:48PM +0530, Vaibhav Hiremath wrote: > > > > > > On Monday 15 August 2016 02:43 PM, Peter Chen wrote: > > >Hi all, > > > > > >This is a follow-up for my last power sequence framework patch set [1]. > > >According to Rob Herring and Ulf Hansson's comments[2], I use a generic > > >power sequence library for parsing the power sequence elements on DT, > > >and implement generic power sequence on library. The host driver > > >can allocate power sequence instance, and calls pwrseq APIs accordingly. > > > > > >In future, if there are special power sequence requirements, the special > > >power sequence library can be created. > > > > > >This patch set is tested on i.mx6 sabresx evk using a dts change, I use > > >two hot-plug devices to simulate this use case, the related binding > > >change is updated at patch [1/6], The udoo board changes were tested > > >using my last power sequence patch set.[3] > > > > > >Except for hard-wired MMC and USB devices, I find the USB ULPI PHY also > > >need to power on itself before it can be found by ULPI bus. > > > > > >[1] http://www.spinics.net/lists/linux-usb/msg142755.html > > >[2] http://www.spinics.net/lists/linux-usb/msg143106.html > > >[3] http://www.spinics.net/lists/linux-usb/msg142815.html > > (Please ignore my response on V2) > > > > Sorry being so late in the discussion... > > > > If I am not missing anything, then I am afraid to say that the > > generic library > > implementation in this patch series is not going to solve many of > > the custom > > requirement of power on, off, etc... > > I know you mentioned about adding another library when we come > > across such platforms, but should we not keep provision (or easy > > hooks/path) > > to enable that ? > > > > Let me bring in the use case I am dealing with, > > > > > > Host > > | > > V > > USB port > > ------------------------------------------------------------ > > | > > V > > USB HUB device (May need custom on/off seq) > > | > > V > > ============================= > > | | > > V V > > Device-1 Device-2 > > (Needs special power (Needs special power > > on/off sequence. on/off sequence. > > Also may need custom Also, may need custom > > sequence for sequence for > > suspend/resume) suspend/resume) > > > > > > Note: Both Devices are connected to HUB via HSIC and may differ > > in terms of functionality, features they support. > > > > In the above case, both Device-1 and Device-2, need separate > > power on/off sequence. So generic library currently we have in this > > patch series is not going to satisfy the need here. > > > > I looked at all 6 revisions of this patch-series, went through the > > review comments, and looked at MMC power sequence code; > > what I can say here is, we need something similar to > > MMC power sequence here, where every device can have its own > > power sequence (if needed). > > > > I know Rob is not in favor of creating platform device for > > this, and I understand his comment. > > If not platform device, but atleast we need mechanism to > > connect each device back to its of_node and its respective > > driver/library fns. For example, the Devices may support different > > boot modes, and platform driver needs to make sure that > > the right sequence is followed for booting. > > > > Peter, My apologies for taking you back again on this series. > > I am OK, if you wish to address this in incremental addition, > > but my point is, we know that the current generic way is not > > enough for us, so I think we should try to fix it in initial phase only. > > > > Rob, it seems generic power sequence can't cover all cases. > Without information from DT, we can't know which power sequence > for which device. > Vaibhav, do you agree that I create pwrseq library list using postcore_initcall for each library, and choose pwrseq library according to compatible string first, if there is no compatible string for this library, just use generic pwrseq library. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
