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[155.4.221.67]) by smtp.gmail.com with ESMTPSA id 135sm2528372wmi.1.2017.04.18.05.32.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 18 Apr 2017 05:32:07 -0700 (PDT) From: Ulf Hansson To: linux-mmc@vger.kernel.org, Ulf Hansson Cc: Jaehoon Chung , Adrian Hunter , Brian Norris , Shawn Lin , Doug Anderson Subject: [PATCH 1/3] mmc: sdio: Add API to manage SDIO IRQs from a workqueue Date: Tue, 18 Apr 2017 14:32:02 +0200 Message-Id: <1492518724-30511-2-git-send-email-ulf.hansson@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1492518724-30511-1-git-send-email-ulf.hansson@linaro.org> References: <1492518724-30511-1-git-send-email-ulf.hansson@linaro.org> For hosts not supporting MMC_CAP2_SDIO_IRQ_NOTHREAD but MMC_CAP_SDIO_IRQ, the SDIO IRQs are processed from a dedicated kernel thread. For these cases, the host calls mmc_signal_sdio_irq() from its ISR to signal a new SDIO IRQ. Signaling an SDIO IRQ makes the host's ->enable_sdio_irq() callback to be invoked to temporary disable the IRQs, before the kernel thread is woken up to process it. When processing of the IRQs are completed, they are re-enabled by the kernel thread, again via invoking the host's ->enable_sdio_irq(). The observation from this, is that the execution path is being unnecessary complex, as the host driver already knows that it needs to temporary disable the IRQs before signaling a new one. Moreover, replacing the kernel thread with a work/workqueue would greatly simplify the code. To address the above problems, let's continue to build upon the support for MMC_CAP2_SDIO_IRQ_NOTHREAD, as it already implements SDIO IRQs to be processed without using the clumsy kernel thread, but it also avoids the ping-ponging calls of the host's ->enable_sdio_irq() callback for each processed IRQ. Therefore, let's add new API sdio_signal_irq(), which enables hosts to signal/process SDIO IRQs by using a work/workqueue, rather than using the kernel thread. Add also a new host callback ->ack_sdio_irq(), which the work invokes when the SDIO IRQs are processed. This informs the host about when it can re-enable the SDIO IRQs. Potentially, we could re-use the existing ->enable_sdio_irq() callback for this matter, however it has turned out that it's more convenient for hosts to get this information via a separate callback. Hosts needs to enable MMC_CAP2_SDIO_IRQ_NOTHREAD to use this new feature, however the feature is optional for already existing hosts suppporting MMC_CAP2_SDIO_IRQ_NOTHREAD. It's likely that all host can convert to use MMC_CAP2_SDIO_IRQ_NOTHREAD and benefit from this feature. Further changes will have to tell. Until then the old path using the kernel thread remains possible. Signed-off-by: Ulf Hansson --- drivers/mmc/core/host.c | 2 ++ drivers/mmc/core/sdio_irq.c | 32 ++++++++++++++++++++++++++++++-- drivers/mmc/core/sdio_ops.h | 2 ++ include/linux/mmc/host.h | 3 +++ 4 files changed, 37 insertions(+), 2 deletions(-) -- 2.7.4 diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index 3f8c85d..77058cb 100644 --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -30,6 +30,7 @@ #include "host.h" #include "slot-gpio.h" #include "pwrseq.h" +#include "sdio_ops.h" #define cls_dev_to_mmc_host(d) container_of(d, struct mmc_host, class_dev) @@ -379,6 +380,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) spin_lock_init(&host->lock); init_waitqueue_head(&host->wq); INIT_DELAYED_WORK(&host->detect, mmc_rescan); + INIT_WORK(&host->sdio_irq_work, sdio_irq_work); setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host); /* diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c index 6d4b720..1b6006d 100644 --- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -92,15 +92,43 @@ static int process_sdio_pending_irqs(struct mmc_host *host) return ret; } -void sdio_run_irqs(struct mmc_host *host) +static void __sdio_run_irqs(struct mmc_host *host) { - mmc_claim_host(host); host->sdio_irq_pending = true; process_sdio_pending_irqs(host); +} + +void sdio_run_irqs(struct mmc_host *host) +{ + mmc_claim_host(host); + __sdio_run_irqs(host); mmc_release_host(host); } EXPORT_SYMBOL_GPL(sdio_run_irqs); +void sdio_irq_work(struct work_struct *work) +{ + struct mmc_host *host = + container_of(work, struct mmc_host, sdio_irq_work); + + mmc_claim_host(host); + __sdio_run_irqs(host); + if (host->ops->ack_sdio_irq) + host->ops->ack_sdio_irq(host); + mmc_release_host(host); +} + +void sdio_signal_irq(struct mmc_host *host) +{ + /* + * The system_freezable_wq helps us to avoid processing IRQs while being + * system PM suspended. Instead these IRQs becomes deferred and managed + * when userspace is unfrozen. + */ + queue_work(system_freezable_wq, &host->sdio_irq_work); +} +EXPORT_SYMBOL_GPL(sdio_signal_irq); + static int sdio_irq_thread(void *_host) { struct mmc_host *host = _host; diff --git a/drivers/mmc/core/sdio_ops.h b/drivers/mmc/core/sdio_ops.h index bed8a83..836e405 100644 --- a/drivers/mmc/core/sdio_ops.h +++ b/drivers/mmc/core/sdio_ops.h @@ -17,6 +17,7 @@ struct mmc_host; struct mmc_card; +struct work_struct; int mmc_send_io_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr); int mmc_io_rw_direct(struct mmc_card *card, int write, unsigned fn, @@ -25,6 +26,7 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, unsigned addr, int incr_addr, u8 *buf, unsigned blocks, unsigned blksz); int sdio_reset(struct mmc_host *host); unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz); +void sdio_irq_work(struct work_struct *work); static inline bool mmc_is_io_op(u32 opcode) { diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 21385ac..f03df539 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -130,6 +130,7 @@ struct mmc_host_ops { int (*get_cd)(struct mmc_host *host); void (*enable_sdio_irq)(struct mmc_host *host, int enable); + void (*ack_sdio_irq)(struct mmc_host *host); /* optional callback for HC quirks */ void (*init_card)(struct mmc_host *host, struct mmc_card *card); @@ -358,6 +359,7 @@ struct mmc_host { unsigned int sdio_irqs; struct task_struct *sdio_irq_thread; + struct work_struct sdio_irq_work; bool sdio_irq_pending; atomic_t sdio_irq_thread_abort; @@ -428,6 +430,7 @@ static inline void mmc_signal_sdio_irq(struct mmc_host *host) } void sdio_run_irqs(struct mmc_host *host); +void sdio_signal_irq(struct mmc_host *host); #ifdef CONFIG_REGULATOR int mmc_regulator_get_ocrmask(struct regulator *supply);