Hi Pierre, I think the runtime pm should not have any dependency with clock gating. Even the MMC driver won't clock gate SD/MMC card, host controller should still enter runtime suspend state, right? So if auto suspended delay could be changed by user, then we can use pm_suspend_schedule to specify the latency which is longer than 8 clock cycle.
Thanks Chuanxiao > -----Original Message----- > From: Tardy, Pierre > Sent: Wednesday, January 19, 2011 12:39 AM > To: Dong, Chuanxiao; [email protected] > Cc: [email protected]; [email protected]; [email protected] > Subject: RE: [PATCH v1 1/3]mmc: implemented runtime pm for mmc host > > > > I'm also worried about this patch not taking in account the 8 clock > > > cycles before > > > shutting down the clock, contrary to the clock gating fw. > > > If you power down hc, you will also gate the clock. So the sdio protocol > > > might not > be > > > strictly followed. > > As mmc spec said, 8 clock cycles is needed. That is right. > > But I think if we have set the auto suspended delay for host, runtime pm > > core > could make sure host to > > wait at least the auto suspended delay before shutting down the power of the > device. So if the auto > > suspended delay is longer than 8 clock cycles, the mmc protocol can be > > followed, > right? > I disagree. You cannot enforce this. It depends on clock speed, that can vary > with > sdio cards. > User can change the autosuspend delay to whatever he wants, it should just > change performance, but not functionality. > > Why don't you just take my clock gating version? > Its working well, I'm using this for 2 weeks, and follow the linux-mmc latest > improvement. > > Regards, > Pierre > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
