mmc: add support for scheduling mmcqd on idle CPU

In order to boost mmc performance on various platforms,
add support for configuring whether set_wake_up_idle()
should be called on the mmc queue thread (mmcqd).
The decision will be set in each individual platform's
dts file.

CRs-Fixed: 787554
Change-Id: I3989d3f5b8228785e6d3bc49c7eb01ebf2fa2f38
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>
[subhashj@codeaurora.org: fixed trivial merge conflicts]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>

Documentation/devicetree/bindings/mmc/sdhci-msm.txt

@@ -75,6 +75,9 @@ In the following, <supply> can be vdd (flash core voltage) or vdd-io (I/O voltag
 	- qcom,large-address-bus - specifies whether the soc is capable of
 				 supporting larger than 32 bit address bus width.
 
+	- qcom,wakeup-on-idle: if configured, the mmcqd thread will call
+	  set_wake_up_idle(), thereby voting for it to be called on idle CPUs.
+
 Example:
 
 	aliases {

drivers/mmc/card/queue.c

@@ -59,6 +59,7 @@ static int mmc_queue_thread(void *d)
 {
 	struct mmc_queue *mq = d;
 	struct request_queue *q = mq->queue;
+	struct mmc_card *card = mq->card;
 	struct sched_param scheduler_params = {0};
 
 	scheduler_params.sched_priority = 1;
@@ -66,6 +67,8 @@ static int mmc_queue_thread(void *d)
 	sched_setscheduler(current, SCHED_FIFO, &scheduler_params);
 
 	current->flags |= PF_MEMALLOC;
+	if (card->host->wakeup_on_idle)
+		set_wake_up_idle(true);
 
 	down(&mq->thread_sem);
 	do {

drivers/mmc/host/sdhci-msm.c

@@ -1367,7 +1367,9 @@ static void sdhci_msm_populate_affinity_type(struct sdhci_msm_pltfm_data *pdata,
 #endif
 
 /* Parse platform data */
-static struct sdhci_msm_pltfm_data *sdhci_msm_populate_pdata(struct device *dev)
+static
+struct sdhci_msm_pltfm_data *sdhci_msm_populate_pdata(struct device *dev,
+						struct sdhci_msm_host *msm_host)
 {
 	struct sdhci_msm_pltfm_data *pdata = NULL;
 	struct device_node *np = dev->of_node;
@@ -1477,6 +1479,9 @@ static struct sdhci_msm_pltfm_data *sdhci_msm_populate_pdata(struct device *dev)
 
 	sdhci_msm_populate_affinity_type(pdata, np);
 
+	if (of_property_read_bool(np, "qcom,wakeup-on-idle"))
+		msm_host->mmc->wakeup_on_idle = true;
+
 	return pdata;
 out:
 	return NULL;
@@ -2822,7 +2827,8 @@ static int sdhci_msm_probe(struct platform_device *pdev)
 			goto pltfm_free;
 		}
 
-		msm_host->pdata = sdhci_msm_populate_pdata(&pdev->dev);
+		msm_host->pdata = sdhci_msm_populate_pdata(&pdev->dev,
+							   msm_host);
 		if (!msm_host->pdata) {
 			dev_err(&pdev->dev, "DT parsing error\n");
 			goto pltfm_free;

include/linux/mmc/host.h

@@ -458,6 +458,7 @@ struct mmc_host {
 		enum mmc_load	state;
 	} clk_scaling;
 	enum dev_state dev_status;
+	bool			wakeup_on_idle;
 	unsigned long		private[0] ____cacheline_aligned;
 };