[PATCH 1/3] mmc: host: Introduce the request_atomic() for the host

[Baolin Wang]

The SD host controller can process one request in the atomic context if
the card is nonremovable, which means we can submit next request in the
irq hard handler when using the MMC software queue to reduce the latency.
Thus this patch adds a new API request_atomic() for the host controller
and implement it for the SD host controller.

Suggested-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Signed-off-by: Baolin Wang <baolin.wang7@xxxxxxxxx>
---
 drivers/mmc/host/sdhci.c |   27 +++++++++++++++++++--------
 drivers/mmc/host/sdhci.h |    1 +
 include/linux/mmc/host.h |    3 +++
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 64bef96..004f789 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1810,17 +1810,12 @@ void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
  *                                                                           *
 \*****************************************************************************/
 
-void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
+static void sdhci_start_request(struct mmc_host *mmc, struct mmc_request *mrq,
+				int present)
 {
-	struct sdhci_host *host;
-	int present;
+	struct sdhci_host *host = mmc_priv(mmc);
 	unsigned long flags;
 
-	host = mmc_priv(mmc);
-
-	/* Firstly check card presence */
-	present = mmc->ops->get_cd(mmc);
-
 	spin_lock_irqsave(&host->lock, flags);
 
 	sdhci_led_activate(host);
@@ -1848,6 +1843,22 @@ void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 
 	spin_unlock_irqrestore(&host->lock, flags);
 }
+
+void sdhci_request_atomic(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	sdhci_start_request(mmc, mrq, 1);
+}
+EXPORT_SYMBOL_GPL(sdhci_request_atomic);
+
+void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	int present;
+
+	/* Firstly check card presence */
+	present = mmc->ops->get_cd(mmc);
+
+	sdhci_start_request(mmc, mrq, present);
+}
 EXPORT_SYMBOL_GPL(sdhci_request);
 
 void sdhci_set_bus_width(struct sdhci_host *host, int width)
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index a73ce89..cecc64b 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -765,6 +765,7 @@ void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
 void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
 			   unsigned short vdd);
 void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq);
+void sdhci_request_atomic(struct mmc_host *mmc, struct mmc_request *mrq);
 void sdhci_set_bus_width(struct sdhci_host *host, int width);
 void sdhci_reset(struct sdhci_host *host, u8 mask);
 void sdhci_set_uhs_signaling(struct sdhci_host *host, unsigned timing);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 3931aa3..cc1a79b 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -92,6 +92,9 @@ struct mmc_host_ops {
 			    int err);
 	void	(*pre_req)(struct mmc_host *host, struct mmc_request *req);
 	void	(*request)(struct mmc_host *host, struct mmc_request *req);
+	/* Submit one request to host in atomic context. */
+	void	(*request_atomic)(struct mmc_host *host,
+				  struct mmc_request *req);
 
 	/*
 	 * Avoid calling the next three functions too often or in a "fast
-- 
1.7.9.5