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

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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: Sujit Reddy Thumma <sthumma@codeaurora.org>
[subhashj@codeaurora.org: fixed minor merge conflict]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
This commit is contained in:
Sujit Reddy Thumma 2013-06-19 20:25:38 +05:30 • committed by Subhash Jadavani
parent 0c196acfcb
commit 9102d4a526
2 changed files with 40 additions and 0 deletions
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38
drivers/mmc/host/sdhci.c
View file

@ -156,6 +156,33 @@ 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 *
@ -3633,7 +3660,18 @@ 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",

2
drivers/mmc/host/sdhci.h
View file

@ -574,6 +574,8 @@ struct sdhci_host {
ktime_t data_start_time;
unsigned int pm_qos_timeout_us; /* timeout for PM QoS request */
struct device_attribute pm_qos_tout;
enum sdhci_power_policy power_policy;
unsigned long private[0] ____cacheline_aligned;