> -----Original Message----- > From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx] > Sent: Thursday, July 30, 2009 2:40 AM > To: Madhusudhan > Cc: 'Andrew Morton'; Lavinen Jarkko (Nokia-D/Helsinki); 'linux-omap > Mailing List'; 'Pierre Ossman'; Karpov Denis.2 (EXT-Teleca/Helsinki); > 'Matt Fleming'; 'lkml' > Subject: Re: [PATCH V2 13/32] omap_hsmmc: context save/restore support > > Madhusudhan wrote: > > > >> -----Original Message----- > >> From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap- > >> owner@xxxxxxxxxxxxxxx] On Behalf Of Adrian Hunter > >> Sent: Tuesday, July 28, 2009 5:40 AM > >> To: Andrew Morton > >> Cc: Jarkko Lavinen; Adrian Hunter; linux-omap Mailing List; Pierre > Ossman; > >> Denis Karpov; Matt Fleming; lkml > >> Subject: [PATCH V2 13/32] omap_hsmmc: context save/restore support > >> > >> From 43e9fa346d7e386328876a8535dc8619bd1f47ae Mon Sep 17 00:00:00 2001 > >> From: Denis Karpov <ext-denis.2.karpov@xxxxxxxxx> > >> Date: Wed, 22 Apr 2009 16:04:25 +0200 > >> Subject: [PATCH] omap_hsmmc: context save/restore support > >> > >> Keep the context over PM dynamic OFF states. > >> > >> Signed-off-by: Denis Karpov <ext-denis.2.karpov@xxxxxxxxx> > >> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> > >> --- > >> drivers/mmc/host/omap_hsmmc.c | 194 > >> ++++++++++++++++++++++++++++++++++++++-- > >> 1 files changed, 184 insertions(+), 10 deletions(-) > >> > >> diff --git a/drivers/mmc/host/omap_hsmmc.c > b/drivers/mmc/host/omap_hsmmc.c > >> index c28d055..ac1a3bf 100644 > >> --- a/drivers/mmc/host/omap_hsmmc.c > >> +++ b/drivers/mmc/host/omap_hsmmc.c > >> @@ -37,6 +37,7 @@ > >> > >> /* OMAP HSMMC Host Controller Registers */ > >> #define OMAP_HSMMC_SYSCONFIG 0x0010 > >> +#define OMAP_HSMMC_SYSSTATUS 0x0014 > >> #define OMAP_HSMMC_CON 0x002C > >> #define OMAP_HSMMC_BLK 0x0104 > >> #define OMAP_HSMMC_ARG 0x0108 > >> @@ -94,6 +95,8 @@ > >> #define DUAL_VOLT_OCR_BIT 7 > >> #define SRC (1 << 25) > >> #define SRD (1 << 26) > >> +#define SOFTRESET (1 << 1) > >> +#define RESETDONE (1 << 0) > >> > >> /* > >> * FIXME: Most likely all the data using these _DEVID defines should > come > >> @@ -152,6 +155,8 @@ struct mmc_omap_host { > >> int slot_id; > >> int dbclk_enabled; > >> int response_busy; > >> + int context_loss; > >> + > >> struct omap_mmc_platform_data *pdata; > >> }; > >> > >> @@ -166,6 +171,166 @@ static void omap_mmc_stop_clock(struct > mmc_omap_host > >> *host) > >> dev_dbg(mmc_dev(host->mmc), "MMC Clock is not stoped\n"); > >> } > >> > >> +#ifdef CONFIG_PM > >> + > >> +/* > >> + * Restore the MMC host context, if it was lost as result of a > >> + * power state change. > >> + */ > >> +static int omap_mmc_restore_ctx(struct mmc_omap_host *host) > >> +{ > >> + struct mmc_ios *ios = &host->mmc->ios; > >> + struct omap_mmc_platform_data *pdata = host->pdata; > >> + int context_loss = 0; > >> + u32 hctl, capa, con; > >> + u16 dsor = 0; > >> + unsigned long timeout; > >> + > >> + if (pdata->get_context_loss_count) { > >> + context_loss = pdata->get_context_loss_count(host->dev); > >> + if (context_loss < 0) > >> + return 1; > >> + } > > This seems to restore the context always. The context should be restored > > only if the card was powered OFF, Right? > > Not exactly. The "context" is just the host controller registers, which > get > lost if power management decides to power off the host controller, which > it > will if it decides it is not doing anything. For us, switching off the > functional clock lets PM power off the host controller. The card can be > in > any power state: on, off, card/regulator sleep. > > The context is restored only when it has been lost - see the following > lines. But this is done from the "enable" method, so this is only called > if someone is trying to access the card. > > + dev_dbg(mmc_dev(host->mmc), "context was %slost\n", > + context_loss == host->context_loss ? "not " : ""); > + if (host->context_loss == context_loss) > + return 1; > > And then further down, we skip some things if the card is off: > > + /* Do not initialize card-specific things if the power is off */ > + if (host->power_mode == MMC_POWER_OFF) > + goto out; > > > > The context could also be lost if the CORE transitions to OFF. I assume > that > > case gets handled here without anything extra required if "power_saving" > is > > set to true. Am I right? > > Yes, "power_saving" is not related to "Power Management". "power_saving" > is about controlling the power regulators, which the host controller does > itself without any support from PM. > > To put it another way, "power_saving" and CONFIG_PM can be set > independently > of one another. But the "omap_hsmmc_context_save" and " omap_hsmmc_context_restore" are under CONFIG_PM. They are empty functions if CONFIG_PM is not set. Does this mean that if CONFIG_PM is not set the host regulators are not turned OFF even if there is no activity on MMC? > > > How about the case of eMMC? Since it is not a removable device the card > is > > not powered OFF. But the CORE OFF would result in context loss. Do we > hit > > the restore_ctx path in that case? > > On the contrary, eMMC *is* powered off. After 100ms of inactivity, eMMC > is > put to card sleep, and the regulator is put to sleep also - in fact there > are two regulators and one is powered off here. After 8 seconds > the other regulator is powered off and consequently after that the eMMC > must > be reinitialised (rescanned) before it can be used. -- 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
