Hi
On 04/21/2016 06:08 AM, Jisheng Zhang wrote:
Dear Jarkko,
On Wed, 20 Apr 2016 16:53:08 +0300 Jarkko Nikula wrote:
On 04/14/2016 03:53 PM, Jisheng Zhang wrote:
When pm_runtime_enable() was being called, the device's usage counter
was 0, causing the PM layer to runtime-suspend the device. We then
went on to call i2c_dw_probe() on a suspended device, which could hung.
Fix this by incrementing the usage counter before pm_runtime_enable().
Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-platdrv.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index d656657..00f9e99 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -246,6 +246,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
if (dev->pm_runtime_disabled) {
pm_runtime_forbid(&pdev->dev);
} else {
+ pm_runtime_get_noresume(&pdev->dev);
pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_set_active(&pdev->dev);
pm_runtime_enable() here after pm_runtime_set_active() shouldn't suspend
as far as I understand which made me thinking if there is some other
FWICT, on arm DT platform, the device usage counter is zero at the beginning,
once we enable rpm, the i2c have chance to runtime suspend.
Yes it is same also for ACPI platforms. What I like to understand what
is actually causing the runtime suspend in your case.
If I add delay longer than 1 second between pm_runtime_enable() and
i2c_dw_probe() suspends still happens only after probe finishes. It will
be triggered by the drivers/base/dd.c: driver_probe_device() when code
calls the pm_request_idle().
I'm wondering is it possible there is a race with deferred probe etc.
that is causing the issue you are seeing.
--
Jarkko
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