On Wed, 28 Jan 2015 21:18:40 +0100 Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > On 28 January 2015 at 00:35, NeilBrown <neilb@xxxxxxx> wrote: > > According to section 7.1.2 of > > > > http://www.sandisk.com/media/File/OEM/Manuals/SD_SDIO_specsv1.pdf > > > > In the case where the interrupt mechanism is used to wake the host while > > the card is in a low power state (i.e. no clocks), Both the card and the > > host shall be placed into the 1-bit SD mode prior to stopping the clock. > > > > > > This is particularly important for the Marvell "libertas" wifi chip > > in the GTA04. While in 4-bit mode it will only signal an interrupt > > when the clock is running (which is why setting CLKEXTFREE is > > important). > > In 1-bit mode, the interrupt is asynchronous (explained in OMAP3 > > TRM description of the CIRQ flag to MMCHS_STAT: > > > > In 1-bit mode, interrupt source is asynchronous (can be a source of > > asynchronous wakeup). > > In 4-bit mode, interrupt source is sampled during the interrupt > > cycle. > > > > ) > > > > We cannot simply set 1-bit mode in omap_hsmmc_runtime_suspend > > as that is called under a spinlock, and setting 1-bit mode requires > > a sleeping call to the card. > > > > So: > > - use a work_struct to schedule setting of 1-bit mode > > - intro a 'force_narrow' state flag which transitions: > > 0 -> NARROW_PENDING -> NARROW_FORCED -> 0 > > - have omap_hsmmc_runtime_suspend fail if interrupts are expected > > but bus is not in 1-bit mode. When it fails it schedules > > the work to change the width. and sets NARROW_PENDING > > - when the host is claimed, if NARROW_FORCED is set, restore the > > 4-bit bus > > - When the host is released (disable_fclk), if NARROW_FORCED, > > then suspend immediately, no autosuspend. If NARROW_PENDING, > > clear that flag as the device has obviously just been used. > > I can't give you more detailed comment about this patch(set) yet. Need > to think a bit more first. > > Anyway, I have one concern, see comment below. > > > > > This all allows a graceful and race-free switch to 1-bit mode > > before switching off the clocks, if interrupts are enabled. > > > > With this, I can use my libertas wifi with a 4-bit bus, with > > interrupts and runtime power-management enabled, and get around > > 14Mb/sec throughput (which is the best I've seen). > > > > Signed-off-by: NeilBrown <neil@xxxxxxxxxx> > > --- > > drivers/mmc/host/omap_hsmmc.c | 55 ++++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 53 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c > > index f84cfb01716d..91ddebbec8a3 100644 > > --- a/drivers/mmc/host/omap_hsmmc.c > > +++ b/drivers/mmc/host/omap_hsmmc.c > > @@ -214,6 +214,10 @@ struct omap_hsmmc_host { > > int reqs_blocked; > > int use_reg; > > int req_in_progress; > > + int force_narrow; > > +#define NARROW_PENDING 1 > > +#define NARROW_FORCED 2 > > + struct work_struct width_work; > > unsigned long clk_rate; > > unsigned int flags; > > #define AUTO_CMD23 (1 << 0) /* Auto CMD23 support */ > > @@ -1778,12 +1782,43 @@ static void omap_hsmmc_conf_bus_power(struct omap_hsmmc_host *host) > > set_sd_bus_power(host); > > } > > > > +static void omap_hsmmc_width_work(struct work_struct *work) > > +{ > > + struct omap_hsmmc_host *host = container_of(work, > > + struct omap_hsmmc_host, > > + width_work); > > + atomic_t noblock; > > + > > + atomic_set(&noblock, 1); > > + if (__mmc_claim_host(host->mmc, &noblock)) { > > + /* Device active again */ > > + host->force_narrow = 0; > > + return; > > + } > > + if (host->force_narrow != NARROW_PENDING) { > > + /* Someone claimed and released before we got here */ > > + mmc_release_host(host->mmc); > > + return; > > + } > > + if (sdio_disable_wide(host->mmc->card) == 0) > > + host->force_narrow = NARROW_FORCED; > > + else > > + host->force_narrow = 0; > > + mmc_release_host(host->mmc); > > +} > > + > > static int omap_hsmmc_enable_fclk(struct mmc_host *mmc) > > { > > struct omap_hsmmc_host *host = mmc_priv(mmc); > > > > pm_runtime_get_sync(host->dev); > > > > + if (host->force_narrow == NARROW_FORCED) { > > + if (sdio_enable_4bit_bus(mmc->card) > 0) > > + mmc_set_bus_width(mmc, MMC_BUS_WIDTH_4); > > + host->force_narrow = 0; > > + } > > + > > return 0; > > } > > > > @@ -1791,8 +1826,13 @@ static int omap_hsmmc_disable_fclk(struct mmc_host *mmc) > > { > > struct omap_hsmmc_host *host = mmc_priv(mmc); > > > > - pm_runtime_mark_last_busy(host->dev); > > - pm_runtime_put_autosuspend(host->dev); > > + if (host->force_narrow == NARROW_FORCED) { > > + pm_runtime_put_sync(host->dev); > > + } else { > > + host->force_narrow = 0; > > + pm_runtime_mark_last_busy(host->dev); > > + pm_runtime_put_autosuspend(host->dev); > > + } > > > > return 0; > > } > > @@ -2024,6 +2064,7 @@ static int omap_hsmmc_probe(struct platform_device *pdev) > > host->power_mode = MMC_POWER_OFF; > > host->next_data.cookie = 1; > > host->pbias_enabled = 0; > > + INIT_WORK(&host->width_work, omap_hsmmc_width_work); > > > > ret = omap_hsmmc_gpio_init(mmc, host, pdata); > > if (ret) > > @@ -2311,6 +2352,16 @@ static int omap_hsmmc_runtime_suspend(struct device *dev) > > spin_lock_irqsave(&host->irq_lock, flags); > > if ((host->mmc->caps & MMC_CAP_SDIO_IRQ) && > > (host->flags & HSMMC_SDIO_IRQ_ENABLED)) { > > + if (host->mmc->ios.bus_width != MMC_BUS_WIDTH_1) { > > + /* In 4-bit mode the card need the clock > > + * to deliver interrupts, so it isn't safe > > + * to turn it off. > > + */ > > + host->force_narrow = NARROW_PENDING; > > + schedule_work(&host->width_work); > > + ret = -EBUSY; > > + goto abort; > > >From a host driver perspective, don't you think this a bit too much to > implement to cover this case!? > > I would rather see the host driver to invoke _one_ API provided by the > mmc core, which takes care of the needed things and also tells the > host driver whether it's safe to enter runtime PM suspend state or > not. Could that work? Since posting the patch I've been thinking along those lines too. I hadn't imagined making just a single call from the host driver, but now that I think about it I don't see why not. It should definitely work. I'll re-spin them in the next day or two. Thanks, NeilBrown > > > + } > > /* disable sdio irq handling to prevent race */ > > OMAP_HSMMC_WRITE(host->base, ISE, 0); > > OMAP_HSMMC_WRITE(host->base, IE, 0); > > > > > > Kind regards > Uffe
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