path: root/drivers/i2c
diff options
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-01-03 01:37:34 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-01-10 00:48:25 +0100
commit02e45646d53bdb38bfb47b83765778d3ecb4d3b3 (patch)
tree44f34c5e89f46a22c9a112cb122f75e6cb96b7db /drivers/i2c
parent422cb781e0d0f81789a1cc0f2171611028450f09 (diff)
PM: i2c-designware-platdrv: Optimize power management
Optimize the power management in i2c-designware-platdrv by making it set the DPM_FLAG_SMART_SUSPEND and DPM_FLAG_LEAVE_SUSPENDED which allows some code to be dropped from its PM callbacks. First, setting DPM_FLAG_SMART_SUSPEND causes the intel-lpss driver to avoid resuming i2c-designware-platdrv devices in its ->prepare callback, so they can stay in runtime suspend after that point even if the direct-complete feature is not used for them. It also causes the ACPI PM domain and the PM core to avoid invoking "late" and "noirq" suspend callbacks for these devices if they are in runtime suspend at the beginning of the "late" phase of device suspend during system suspend. That guarantees dw_i2c_plat_suspend() to be called for a device only if it is not in runtime suspend. Moreover, it causes the device's runtime PM status to be set to "active" after calling dw_i2c_plat_resume() for it, so the driver doesn't need internal flags to avoid invoking either dw_i2c_plat_suspend() or dw_i2c_plat_resume() twice in a row. Second, setting DPM_FLAG_LEAVE_SUSPENDED enables the optimization allowing the device to stay suspended after system resume under suitable conditions, so again the driver doesn't need to take care of that by itself. Accordingly, the internal "suspended" and "skip_resume" flags used by the driver are not necessary any more, so drop them and simplify the driver's PM callbacks. Additionally, notice that dw_i2c_plat_complete() only needs to schedule runtime PM resume for the device if platform firmware has been involved in resuming the system, so make it call pm_resume_via_firmware() to check that. Also make it check the runtime PM status of the device instead of its direct_complete flag which also works if the device remained suspended due to the DPM_FLAG_LEAVE_SUSPENDED driver flag. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com> Acked-by: Wolfram Sang <wsa@the-dreams.de> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Diffstat (limited to 'drivers/i2c')
2 files changed, 12 insertions, 21 deletions
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 21bf619a86c5..9fee4c054d3d 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -280,8 +280,6 @@ struct dw_i2c_dev {
int (*acquire_lock)(struct dw_i2c_dev *dev);
void (*release_lock)(struct dw_i2c_dev *dev);
bool pm_disabled;
- bool suspended;
- bool skip_resume;
void (*disable)(struct dw_i2c_dev *dev);
void (*disable_int)(struct dw_i2c_dev *dev);
int (*init)(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 4f90a6dc186f..153b947702c5 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -42,6 +42,7 @@
#include <linux/reset.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/suspend.h>
#include "i2c-designware-core.h"
@@ -372,7 +373,10 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
adap->dev.of_node = pdev->dev.of_node;
- dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_SMART_PREPARE);
+ dev_pm_set_driver_flags(&pdev->dev,
/* The code below assumes runtime PM to be disabled. */
@@ -448,7 +452,13 @@ static int dw_i2c_plat_prepare(struct device *dev)
static void dw_i2c_plat_complete(struct device *dev)
- if (dev->power.direct_complete)
+ /*
+ * The device can only be in runtime suspend at this point if it has not
+ * been resumed throughout the ending system suspend/resume cycle, so if
+ * the platform firmware might mess up with it, request the runtime PM
+ * framework to resume it.
+ */
+ if (pm_runtime_suspended(dev) && pm_resume_via_firmware())
@@ -461,16 +471,9 @@ static int dw_i2c_plat_suspend(struct device *dev)
struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
- if (i_dev->suspended) {
- i_dev->skip_resume = true;
- return 0;
- }
i2c_dw_plat_prepare_clk(i_dev, false);
- i_dev->suspended = true;
return 0;
@@ -478,19 +481,9 @@ static int dw_i2c_plat_resume(struct device *dev)
struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
- if (!i_dev->suspended)
- return 0;
- if (i_dev->skip_resume) {
- i_dev->skip_resume = false;
- return 0;
- }
i2c_dw_plat_prepare_clk(i_dev, true);
- i_dev->suspended = false;
return 0;

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