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. 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; + } /* disable sdio irq handling to prevent race */ OMAP_HSMMC_WRITE(host->base, ISE, 0); OMAP_HSMMC_WRITE(host->base, IE, 0); -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
