"Madhusudhan" <madhu.cr@xxxxxx> writes: >> -----Original Message----- >> From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap- >> owner@xxxxxxxxxxxxxxx] On Behalf Of Kevin Hilman >> Sent: Tuesday, February 23, 2010 6:51 PM >> To: linux-omap@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH/RFC 0/4] convert HS-MMC driver to hwmod + runtime PM >> >> Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> writes: >> >> > This series converts the OMAP HS-MMC driver to use omap_hwmod + >> > runtime PM API. >> > >> > Depends on MMC hwmods available in 'pm-wip/hwmods' branch of >> > my git tree[1] as well as previously posted runtime PM series: >> > >> > [PATCH/RFC 0/2] initial runtime PM layer for OMAP >> > >> > The easies way to experiment/test is to use my 'pm-wip/mmc' branch >> > which has all the dependencies, and is based on omap/for-next'. >> > It has been tested by merging with current PM branch. >> > >> > [1] http://git.kernel.org/?p=linux/kernel/git/khilman/linux-omap-pm.git >> > >> >> A question for those of you who actually understand the MMC driver... >> I'm having problems getting my head around the current PM stuff in the >> MMC driver. My primary question is: >> >> Why does the suspend hook need to re-enable the device before >> suspending? >> > > In the scenario where there is no activity on the bus the MMC clocks are > kept disabled. Now in the suspend path the MMC core will issue certain CMDs > like CMD7(to end the suspend path) to deselect the card(more of a protocol > stuff). Hence the host need to be in enabled state before letting the core > know that there is a suspend request. I guess what I'm wondering is whether we can (should) have the exact same path for runtime PM (idle) and static PM (suspend/resume.) My current approach is that the suspend is a NOP if the device is already runtime suspended. >> When using runtime PM, the MMC device is disabled including >> clocks off and regulator off (if power_savings == true) when there >> is no activity. >> >> Then, in the static suspend hook, it's re-enabled (including taking it out >> of >> off, re-enabling regulators etc) only to be quickly disabled again. >> This seems horribly inefficient. >> > > This is exactly for the reason I mentioned above. > >> I admit to not understanding the MMC layer terribly well, so can someone >> enlighten me as to what is going on here? >> >> What I am testing here is a patch on top of this series (below) that >> adds a check to the static suspend hook. If the device is already >> runtime suspended, then the suspend and resume hooks should be noop. >> >> This appears to work just fine while testing on omap3evm just doing >> simple read/write tests before an after suspend resume. >> > > I did some basic testing with your previously posted patches. But my testing > was incomplete because on Zoom2 because for some reason the OFF mode was not > working even without your patches. OK, I will try on Zoom2. I've only tested this so far on OMAP3EVM. > My concern was more with respect to OFF mode in idle path since your patches > removed context restore calls if I recall correctly. No, I didn't remove restore. I just moved it into the runtime PM resume callback. > Are you able to hit CORE OFF and then come back and do the > read/write transfers in idle as well as suspend/resume path? Yes. Kevin > >> Note that if you want to test this patch, it also depends on this >> patch to runtime PM from the linux-pm list: >> https://lists.linux-foundation.org/pipermail/linux-pm/2010- >> February/024275.html >> >> These are all included in an updated version of my pm-wip/mmc branch >> for ease of testing. Merge it with the current PM branch, enable >> CONFIG_PM_RUNTIME and test away. >> >> Kevin >> >> commit 166cba7679fa267ee6e6eb39fd1e871ede5ded16 >> Author: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> >> Date: Tue Feb 23 16:21:56 2010 -0800 >> >> MMC: omap_hsmmc: check for runtime-suspend in static suspend >> >> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c >> index 16d66b9..dd027bb 100644 >> --- a/drivers/mmc/host/omap_hsmmc.c >> +++ b/drivers/mmc/host/omap_hsmmc.c >> @@ -2222,6 +2222,9 @@ static int omap_hsmmc_suspend(struct device *dev) >> if (host && host->suspended) >> return 0; >> >> + if (pm_is_runtime_suspended(host->dev)) >> + return 0; >> + >> if (host) { >> host->suspended = 1; >> if (host->pdata->suspend) { >> @@ -2260,12 +2263,6 @@ static int omap_hsmmc_suspend(struct device *dev) >> } >> mmc_host_disable(host->mmc); >> } >> - >> - /* >> - * HACK: "extra" put to compensate for DPM core keeping >> - * runtime PM disabled. -- khilman >> - */ >> - pm_runtime_put_sync(host->dev); >> } >> return ret; >> } >> @@ -2280,13 +2277,10 @@ static int omap_hsmmc_resume(struct device *dev) >> if (host && !host->suspended) >> return 0; >> >> - if (host) { >> - /* >> - * HACK: "extra" get to compensate for DPM core keeping >> - * runtime PM disabled. -- khilman >> - */ >> - pm_runtime_get_sync(host->dev); >> + if (pm_is_runtime_suspended(host->dev)) >> + return 0; >> >> + if (host) { >> if (mmc_host_enable(host->mmc) != 0) { >> pm_runtime_suspend(host->dev); >> goto clk_en_err; >> >> >> >> -- >> 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 -- 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
