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SubjectRe: [PATCH v2] i2c: designwear: Fix clk warning on suspend/resume
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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@linux.intel.com>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: linux-i2c@vger.kernel.org
> Suggested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> 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.

--
Jarkko

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