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. ) It is awkward to simply set 1-bit mode in ->runtime_suspend as that will call mmc_set_ios which calls ops->set_ios(), which will likely call pm_runtime_get_sync(), on the device that is currently suspending. This deadlocks. So: - create a work_struct to schedule setting of 1-bit mode - introduce an 'sdio_narrowed' state flag which transitions: 0 (normal) -> 1 (convert to 1-bit pending) -> 2 (have switch to 1-bit mode) -> 0 (normal) - create a function mmc_sdio_want_no_clocks() which can be called when the driver wants to turn off clocks (presumably after an idle timeout). This either succeeds (in 1-bit mode) or fails and schedules the work to switch to 1-bit mode. - when the host is claimed, if sdio_narrowed is 2, restore the 4-bit bus - When the host is released, if sdio_narrowed is 1, then some caller other than our worker claimed the host first, so clear sdio_narrowed. This all allows a graceful and race-free switch to 1-bit mode before switching off the clocks, if SDIO interrupts are enabled. A host should call mmc_sdio_want_no_clocks() when about to turn off clocks if sdio interrupts are enabled, and the ->disable() function should not use a timeout (pm_runtime_put_autosuspend) if ->sdio_narrowed is 2. Signed-off-by: NeilBrown <neil@xxxxxxxxxx> --- drivers/mmc/core/core.c | 18 ++++++++++++++---- drivers/mmc/core/sdio.c | 42 +++++++++++++++++++++++++++++++++++++++++- include/linux/mmc/core.h | 2 ++ include/linux/mmc/host.h | 2 ++ 4 files changed, 59 insertions(+), 5 deletions(-) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 541c8903dc6b..0258fdf1a03d 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -921,8 +921,14 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort) wake_up(&host->wq); spin_unlock_irqrestore(&host->lock, flags); remove_wait_queue(&host->wq, &wait); - if (host->ops->enable && !stop && host->claim_cnt == 1) - host->ops->enable(host); + if (!stop && host->claim_cnt == 1) { + if (host->ops->enable) + host->ops->enable(host); + if (atomic_read(&host->sdio_narrowed) == 2) { + sdio_enable_4bit_bus(host->card); + atomic_set(&host->sdio_narrowed, 0); + } + } return stop; } @@ -941,8 +947,12 @@ void mmc_release_host(struct mmc_host *host) WARN_ON(!host->claimed); - if (host->ops->disable && host->claim_cnt == 1) - host->ops->disable(host); + if (host->claim_cnt == 1) { + if (atomic_read(&host->sdio_narrowed) == 1) + atomic_set(&host->sdio_narrowed, 0); + if (host->ops->disable) + host->ops->disable(host); + } spin_lock_irqsave(&host->lock, flags); if (--host->claim_cnt) { diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c index 5bc6c7dbbd60..9761e4d5f49b 100644 --- a/drivers/mmc/core/sdio.c +++ b/drivers/mmc/core/sdio.c @@ -288,7 +288,7 @@ static int sdio_disable_wide(struct mmc_card *card) } -static int sdio_enable_4bit_bus(struct mmc_card *card) +int sdio_enable_4bit_bus(struct mmc_card *card) { int err; @@ -313,6 +313,45 @@ static int sdio_enable_4bit_bus(struct mmc_card *card) return err; } +static void mmc_sdio_width_work(struct work_struct *work) +{ + struct mmc_host *host = container_of(work, struct mmc_host, + sdio_width_work); + atomic_t noblock; + + atomic_set(&noblock, 1); + if (__mmc_claim_host(host, &noblock)) + return; + if (atomic_read(&host->sdio_narrowed) != 1) { + /* Nothing to do */ + mmc_release_host(host); + return; + } + if (sdio_disable_wide(host->card) == 0) + atomic_set(&host->sdio_narrowed, 2); + else + atomic_set(&host->sdio_narrowed, 0); + mmc_release_host(host); +} + +int mmc_sdio_want_no_clocks(struct mmc_host *host) +{ + if (!(host->caps & MMC_CAP_SDIO_IRQ) || + host->ios.bus_width == MMC_BUS_WIDTH_1) + /* Safe to turn off clocks */ + return 1; + + + /* In 4-bit mode the card needs the clock + * to deliver interrupts, so it isn't safe + * to turn of clocks just yet + */ + atomic_add_unless(&host->sdio_narrowed, 1, 1); + + schedule_work(&host->sdio_width_work); + return 0; +} +EXPORT_SYMBOL_GPL(mmc_sdio_want_no_clocks); /* * Test if the card supports high-speed mode and, if so, switch to it. @@ -1100,6 +1139,7 @@ int mmc_attach_sdio(struct mmc_host *host) goto err; } + INIT_WORK(&host->sdio_width_work, mmc_sdio_width_work); /* * Detect and init the card. */ diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h index 160448f920ac..faf6d1be0971 100644 --- a/include/linux/mmc/core.h +++ b/include/linux/mmc/core.h @@ -212,4 +212,6 @@ struct device_node; extern u32 mmc_vddrange_to_ocrmask(int vdd_min, int vdd_max); extern int mmc_of_parse_voltage(struct device_node *np, u32 *mask); +extern int sdio_enable_4bit_bus(struct mmc_card *card); +extern int mmc_sdio_want_no_clocks(struct mmc_host *host); #endif /* LINUX_MMC_CORE_H */ diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 0c8cbe5d1550..7e6a54c49a15 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -350,6 +350,8 @@ struct mmc_host { struct task_struct *sdio_irq_thread; bool sdio_irq_pending; atomic_t sdio_irq_thread_abort; + struct work_struct sdio_width_work; + atomic_t sdio_narrowed; /* 1==pending, 2==complete*/ mmc_pm_flag_t pm_flags; /* requested pm features */ -- 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
