+++ /dev/null
-From 0cc2b4e5a020fc7f4d1795741c116c983e9467d7 Mon Sep 17 00:00:00 2001
-From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
-Date: Tue, 24 Oct 2017 15:20:45 +0200
-Subject: PM / QoS: Fix device resume latency PM QoS
-
-From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-
-commit 0cc2b4e5a020fc7f4d1795741c116c983e9467d7 upstream.
-
-The special value of 0 for device resume latency PM QoS means
-"no restriction", but there are two problems with that.
-
-First, device resume latency PM QoS requests with 0 as the
-value are always put in front of requests with positive
-values in the priority lists used internally by the PM QoS
-framework, causing 0 to be chosen as an effective constraint
-value. However, that 0 is then interpreted as "no restriction"
-effectively overriding the other requests with specific
-restrictions which is incorrect.
-
-Second, the users of device resume latency PM QoS have no
-way to specify that *any* resume latency at all should be
-avoided, which is an artificial limitation in general.
-
-To address these issues, modify device resume latency PM QoS to
-use S32_MAX as the "no constraint" value and 0 as the "no
-latency at all" one and rework its users (the cpuidle menu
-governor, the genpd QoS governor and the runtime PM framework)
-to follow these changes.
-
-Also add a special "n/a" value to the corresponding user space I/F
-to allow user space to indicate that it cannot accept any resume
-latencies at all for the given device.
-
-Fixes: 85dc0b8a4019 (PM / QoS: Make it possible to expose PM QoS latency constraints)
-Link: https://bugzilla.kernel.org/show_bug.cgi?id=197323
-Reported-by: Reinette Chatre <reinette.chatre@intel.com>
-Tested-by: Reinette Chatre <reinette.chatre@intel.com>
-Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-Acked-by: Alex Shi <alex.shi@linaro.org>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- Documentation/ABI/testing/sysfs-devices-power | 4 +
- drivers/base/cpu.c | 3 -
- drivers/base/power/domain_governor.c | 53 ++++++++++++++------------
- drivers/base/power/qos.c | 2
- drivers/base/power/runtime.c | 2
- drivers/base/power/sysfs.c | 25 ++++++++++--
- drivers/cpuidle/governors/menu.c | 4 -
- include/linux/pm_qos.h | 5 +-
- 8 files changed, 63 insertions(+), 35 deletions(-)
-
---- a/Documentation/ABI/testing/sysfs-devices-power
-+++ b/Documentation/ABI/testing/sysfs-devices-power
-@@ -211,7 +211,9 @@ Description:
- device, after it has been suspended at run time, from a resume
- request to the moment the device will be ready to process I/O,
- in microseconds. If it is equal to 0, however, this means that
-- the PM QoS resume latency may be arbitrary.
-+ the PM QoS resume latency may be arbitrary and the special value
-+ "n/a" means that user space cannot accept any resume latency at
-+ all for the given device.
-
- Not all drivers support this attribute. If it isn't supported,
- it is not present.
---- a/drivers/base/cpu.c
-+++ b/drivers/base/cpu.c
-@@ -377,7 +377,8 @@ int register_cpu(struct cpu *cpu, int nu
-
- per_cpu(cpu_sys_devices, num) = &cpu->dev;
- register_cpu_under_node(num, cpu_to_node(num));
-- dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
-+ dev_pm_qos_expose_latency_limit(&cpu->dev,
-+ PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
-
- return 0;
- }
---- a/drivers/base/power/domain_governor.c
-+++ b/drivers/base/power/domain_governor.c
-@@ -14,23 +14,20 @@
- static int dev_update_qos_constraint(struct device *dev, void *data)
- {
- s64 *constraint_ns_p = data;
-- s32 constraint_ns = -1;
-+ s64 constraint_ns = -1;
-
- if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
- constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
-
-- if (constraint_ns < 0) {
-+ if (constraint_ns < 0)
- constraint_ns = dev_pm_qos_read_value(dev);
-- constraint_ns *= NSEC_PER_USEC;
-- }
-- if (constraint_ns == 0)
-+
-+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
- return 0;
-
-- /*
-- * constraint_ns cannot be negative here, because the device has been
-- * suspended.
-- */
-- if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
-+ constraint_ns *= NSEC_PER_USEC;
-+
-+ if (constraint_ns < *constraint_ns_p || *constraint_ns_p < 0)
- *constraint_ns_p = constraint_ns;
-
- return 0;
-@@ -63,10 +60,14 @@ static bool default_suspend_ok(struct de
-
- spin_unlock_irqrestore(&dev->power.lock, flags);
-
-- if (constraint_ns < 0)
-+ if (constraint_ns == 0)
- return false;
-
-- constraint_ns *= NSEC_PER_USEC;
-+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
-+ constraint_ns = -1;
-+ else
-+ constraint_ns *= NSEC_PER_USEC;
-+
- /*
- * We can walk the children without any additional locking, because
- * they all have been suspended at this point and their
-@@ -76,14 +77,19 @@ static bool default_suspend_ok(struct de
- device_for_each_child(dev, &constraint_ns,
- dev_update_qos_constraint);
-
-- if (constraint_ns > 0) {
-- constraint_ns -= td->suspend_latency_ns +
-- td->resume_latency_ns;
-- if (constraint_ns == 0)
-- return false;
-+ if (constraint_ns < 0) {
-+ /* The children have no constraints. */
-+ td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
-+ td->cached_suspend_ok = true;
-+ } else {
-+ constraint_ns -= td->suspend_latency_ns + td->resume_latency_ns;
-+ if (constraint_ns > 0) {
-+ td->effective_constraint_ns = constraint_ns;
-+ td->cached_suspend_ok = true;
-+ } else {
-+ td->effective_constraint_ns = 0;
-+ }
- }
-- td->effective_constraint_ns = constraint_ns;
-- td->cached_suspend_ok = constraint_ns >= 0;
-
- /*
- * The children have been suspended already, so we don't need to take
-@@ -145,13 +151,14 @@ static bool __default_power_down_ok(stru
- td = &to_gpd_data(pdd)->td;
- constraint_ns = td->effective_constraint_ns;
- /* default_suspend_ok() need not be called before us. */
-- if (constraint_ns < 0) {
-+ if (constraint_ns < 0)
- constraint_ns = dev_pm_qos_read_value(pdd->dev);
-- constraint_ns *= NSEC_PER_USEC;
-- }
-- if (constraint_ns == 0)
-+
-+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
- continue;
-
-+ constraint_ns *= NSEC_PER_USEC;
-+
- /*
- * constraint_ns cannot be negative here, because the device has
- * been suspended.
---- a/drivers/base/power/qos.c
-+++ b/drivers/base/power/qos.c
-@@ -189,7 +189,7 @@ static int dev_pm_qos_constraints_alloca
- plist_head_init(&c->list);
- c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
- c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
-- c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
-+ c->no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
- c->type = PM_QOS_MIN;
- c->notifiers = n;
-
---- a/drivers/base/power/runtime.c
-+++ b/drivers/base/power/runtime.c
-@@ -253,7 +253,7 @@ static int rpm_check_suspend_allowed(str
- || (dev->power.request_pending
- && dev->power.request == RPM_REQ_RESUME))
- retval = -EAGAIN;
-- else if (__dev_pm_qos_read_value(dev) < 0)
-+ else if (__dev_pm_qos_read_value(dev) == 0)
- retval = -EPERM;
- else if (dev->power.runtime_status == RPM_SUSPENDED)
- retval = 1;
---- a/drivers/base/power/sysfs.c
-+++ b/drivers/base/power/sysfs.c
-@@ -218,7 +218,14 @@ static ssize_t pm_qos_resume_latency_sho
- struct device_attribute *attr,
- char *buf)
- {
-- return sprintf(buf, "%d\n", dev_pm_qos_requested_resume_latency(dev));
-+ s32 value = dev_pm_qos_requested_resume_latency(dev);
-+
-+ if (value == 0)
-+ return sprintf(buf, "n/a\n");
-+ else if (value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
-+ value = 0;
-+
-+ return sprintf(buf, "%d\n", value);
- }
-
- static ssize_t pm_qos_resume_latency_store(struct device *dev,
-@@ -228,11 +235,21 @@ static ssize_t pm_qos_resume_latency_sto
- s32 value;
- int ret;
-
-- if (kstrtos32(buf, 0, &value))
-- return -EINVAL;
-+ if (!kstrtos32(buf, 0, &value)) {
-+ /*
-+ * Prevent users from writing negative or "no constraint" values
-+ * directly.
-+ */
-+ if (value < 0 || value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
-+ return -EINVAL;
-
-- if (value < 0)
-+ if (value == 0)
-+ value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
-+ } else if (!strcmp(buf, "n/a") || !strcmp(buf, "n/a\n")) {
-+ value = 0;
-+ } else {
- return -EINVAL;
-+ }
-
- ret = dev_pm_qos_update_request(dev->power.qos->resume_latency_req,
- value);
---- a/drivers/cpuidle/governors/menu.c
-+++ b/drivers/cpuidle/governors/menu.c
-@@ -298,8 +298,8 @@ static int menu_select(struct cpuidle_dr
- data->needs_update = 0;
- }
-
-- /* resume_latency is 0 means no restriction */
-- if (resume_latency && resume_latency < latency_req)
-+ if (resume_latency < latency_req &&
-+ resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
- latency_req = resume_latency;
-
- /* Special case when user has set very strict latency requirement */
---- a/include/linux/pm_qos.h
-+++ b/include/linux/pm_qos.h
-@@ -27,16 +27,17 @@ enum pm_qos_flags_status {
- PM_QOS_FLAGS_ALL,
- };
-
--#define PM_QOS_DEFAULT_VALUE -1
-+#define PM_QOS_DEFAULT_VALUE (-1)
-+#define PM_QOS_LATENCY_ANY S32_MAX
-
- #define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
- #define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
- #define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
- #define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE 0
- #define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE 0
-+#define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT PM_QOS_LATENCY_ANY
- #define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE 0
- #define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1)
--#define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1))
-
- #define PM_QOS_FLAG_NO_POWER_OFF (1 << 0)
- #define PM_QOS_FLAG_REMOTE_WAKEUP (1 << 1)
projects / thirdparty / kernel / stable-queue.git / commitdiff
