On 06/14/2016 06:07 PM, Ulf Hansson wrote:
In cases when the designware specific flag "pm_runtime_disable" is set,
->probe() calls pm_runtime_forbid() for the device, but without enabling
runtime PM. This increases the runtime PM usage count for the device, but
as runtime PM is disabled it's pointless.
As far as I remember reason for that was to prevent suspending the
device when unloading the driver.
Let's instead convert to unconditionally enable runtime PM, which has the
effect of making a parent device aware of its child.
To also maintain the old behaviour when the "pm_runtime_disable" flag is
set, which prevents userspace to enable runtime PM suspend via sysfs,
switch from calling pm_runtime_forbid() into pm_runtime_get_noresume()
during ->probe().
While changing this, let's also also correct the error path in ->probe()
and fix ->remove(), as to decrease the runtime PM usage count when it has
been in increased by pm_runtime_forbid() (after this change, by
pm_runtime_get_noresume()).
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-platdrv.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 19174e7..94ff953 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -236,21 +236,21 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
adap->dev.of_node = pdev->dev.of_node;
...
+ if (dev->pm_runtime_disabled)
+ pm_runtime_get_noresume(&pdev->dev);
@@ -267,10 +267,11 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
i2c_dw_disable(dev);
+ if (dev->pm_runtime_disabled)
+ pm_runtime_put_noidle(&pdev->dev);
That will trigger power down after returning from dw_i2c_plat_remove()
by looking at debug print from acpi_device_set_power() but now I don't
find what call chain is actually causing it.
Must be something to do with drivers/acpi/acpi_lpss.c and notifier calls
from drivers/base/dd.c. Also I was wondering why RPM usage counts don't
increase monotonically over repeated module load/unload cycle.
I had a few paper notes about these when I last time looked and debugged
PM in i2c-designware but throw away them :-(
--
Jarkko
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