On Wed, Aug 31, 2016 at 01:46:30PM +0530, Vaibhav Hiremath wrote: > > > On Monday 29 August 2016 04:40 PM, Peter Chen wrote: > >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. > > > > Lets hear from MMC folks. Ulf, do you agree on approach > for pwr seq ?? > > > With above approach, I kind of agree on it, but I have couple > of comments, > > - How DTS looks like now ?? Can you put example here ? The dts is the same with current version. > - Should we merge MMC power sequence in next series ? > We also can take this as an incremental change, to avoid further > delay :) We had an agreement that keep mmc's pwrseq framework unchanging. Unless Ulf and rob both agree to change. > - Lets also add suspend/resume callback to struct pwrseq > Why suspend/resume can't do at related driver's suspend/resume API? > > There are some comments I have on the patches, > I will respond directly on respective patches, it would be useful > for next series. > Thanks. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
