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Commit c415b3c9 authored by Sujit Reddy Thumma's avatar Sujit Reddy Thumma Committed by Stephen Boyd
Browse files

mmc: sdhci: Provide sysfs attributes to tune PM QoS unvote timeout 



Provide sysfs tunables to defer PM QoS vote of default value so that
back-to-back requests wouldn't suffer from latencies caused by CPU
power collapse transition states.

Change-Id: I7180c68c1f13240faa5f432335d72e7f6b198183
Signed-off-by: default avatarSujit Reddy Thumma <sthumma@codeaurora.org>
parent 4a561635

drivers/mmc/host/sdhci.c

+38 −0
Original line number Diff line number Diff line
@@ -133,6 +133,33 @@ static void sdhci_dumpregs(struct sdhci_host *host) 
	pr_info(DRIVER_NAME ": ===========================================\n");

}



#define MAX_PM_QOS_TIMEOUT_VALUE	100000 /* 100 ms */

static ssize_t

show_sdhci_pm_qos_tout(struct device *dev, struct device_attribute *attr,

			char *buf)

{

	struct sdhci_host *host = dev_get_drvdata(dev);



	return snprintf(buf, PAGE_SIZE, "%d us\n", host->pm_qos_timeout_us);

}



static ssize_t

store_sdhci_pm_qos_tout(struct device *dev, struct device_attribute *attr,

		const char *buf, size_t count)

{

	struct sdhci_host *host = dev_get_drvdata(dev);

	uint32_t value;

	unsigned long flags;



	if (!kstrtou32(buf, 0, &value)) {

		spin_lock_irqsave(&host->lock, flags);

		if (value <= MAX_PM_QOS_TIMEOUT_VALUE)

			host->pm_qos_timeout_us = value;

		spin_unlock_irqrestore(&host->lock, flags);

	}

	return count;

}



/*****************************************************************************\

 *                                                                           *

 * Low level functions                                                       *
@@ -3592,7 +3619,18 @@ int sdhci_add_host(struct sdhci_host *host) 
		host->pm_qos_timeout_us = 10000; /* default value */

		pm_qos_add_request(&host->pm_qos_req_dma,

				PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);



		host->pm_qos_tout.show = show_sdhci_pm_qos_tout;

		host->pm_qos_tout.store = store_sdhci_pm_qos_tout;

		sysfs_attr_init(&host->pm_qos_tout.attr);

		host->pm_qos_tout.attr.name = "pm_qos_unvote_delay";

		host->pm_qos_tout.attr.mode = S_IRUGO | S_IWUSR;

		ret = device_create_file(mmc_dev(mmc), &host->pm_qos_tout);

		if (ret)

			pr_err("%s: cannot create pm_qos_unvote_delay %d\n",

					mmc_hostname(mmc), ret);

	}



	mmc_add_host(mmc);



	pr_info("%s: SDHCI controller on %s [%s] using %s\n",

include/linux/mmc/sdhci.h

+1 −0
Original line number Diff line number Diff line
@@ -251,6 +251,7 @@ struct sdhci_host { 
	unsigned int cpu_dma_latency_us;

	struct pm_qos_request pm_qos_req_dma;

	unsigned int pm_qos_timeout_us;         /* timeout for PM QoS request */

	struct device_attribute pm_qos_tout;



	struct sdhci_next next_data;

	ktime_t data_start_time;