Re: [PATCH v2] i2c: designwear: Fix clk warning on suspend/resume

From: Jarkko Nikula
Date: Tue Feb 14 2017 - 10:31:08 EST

On 14.02.2017 06:05, John Stultz wrote:
On my HiKey board, I'm seeing clk warnings on suspend/resume,
which seem to be caused by runtime pm suspending the device,
then the same suspend hook being called again on suspend time.

This patch fixes this by setting the SYSTEM_SLEEP_PM_OPS to
using pm_runtime_force_suspend and pm_runtime_force_resume.

Cc: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Cc: linux-i2c@xxxxxxxxxxxxxxx
Suggested-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
v2: Switch to suggested fix by Jarkko.

drivers/i2c/busses/i2c-designware-platdrv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 6ce4313..09f27ec 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -362,7 +362,7 @@ static int dw_i2c_plat_resume(struct device *dev)
static const struct dev_pm_ops dw_i2c_dev_pm_ops = {
.prepare = dw_i2c_plat_prepare,
.complete = dw_i2c_plat_complete,
- SET_SYSTEM_SLEEP_PM_OPS(dw_i2c_plat_suspend, dw_i2c_plat_resume)
+ SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
SET_RUNTIME_PM_OPS(dw_i2c_plat_suspend, dw_i2c_plat_resume, NULL)

We need to hold this a bit. I've been debugging this on our platforms but haven't figured out yet how to fix a regression it is causing with drivers/acpi/acpi_lpss.c :-(

With this change in i2c-designware-platdrv.c the suspend path in acpi_lpss.c changes. First it saves its the register context in acpi_lpss_runtime_suspend() and powers down. Then the device which is now off will save again the register context (now reads full of 0xff...) in acpi_lpss_suspend_late() and restores wrong context (0xff...) when resuming.