Dear Wolfram, Mika,
On Thu, 21 May 2015 14:40:49 +0300
Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> [Adding Jarkko, just in case he has concerns about this]
>
> On Wed, May 20, 2015 at 10:33:13PM +0800, Jisheng Zhang wrote:
> > Commit 1fc2fe204cb9 ("i2c: designware: Add runtime PM hooks") adds
> > runtime pm support using the same ops for system pm and runtime pm.
> > When suspend to ram, the i2c host may have been runtime suspended, thus
> > i2c_dw_disable() hangs.
> >
> > Previously, I fixed this issue by separating ops for system pm and
> > runtime pm, then in the system suspend/resume path, runtime pm apis are
> > used to ensure the device is at correct state.
> >
> > But as Mika Westerberg pointed out: it sounds a bit silly to resume the
> > device just because you want to call i2c_dw_disable() for it before
> > suspending again. He then suggested an elegant solution which keeps the
> > device runtime suspended during system suspend with the help of
> > 'dev->power.direct_complete'. This patch adopted this solution, and in
> > fact Mika provided the main code.
> >
> > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
> > ---
> > v2 change:
> > - adopt Mika's suggestion to make use of direct_complete flag
> >
> > drivers/i2c/busses/i2c-designware-platdrv.c | 33 +++++++++++++++++++++++++----
> > 1 file changed, 29 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index 0a80e4a..f89650f 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -298,6 +298,22 @@ static const struct of_device_id dw_i2c_of_match[] = {
> > MODULE_DEVICE_TABLE(of, dw_i2c_of_match);
> > #endif
> >
> > +#ifdef CONFIG_PM_SLEEP
> > +static int dw_i2c_prepare(struct device *dev)
> > +{
> > + return pm_runtime_suspended(dev);
> > +}
> > +
> > +static void dw_i2c_complete(struct device *dev)
> > +{
> > + if (dev->power.direct_complete)
> > + pm_request_resume(dev);
> > +}
> > +#else
> > +#define dw_i2c_prepare NULL
> > +#define dw_i2c_complete NULL
> > +#endif
> > +
> > #ifdef CONFIG_PM
> > static int dw_i2c_suspend(struct device *dev)
> > {
> > @@ -322,10 +338,19 @@ static int dw_i2c_resume(struct device *dev)
> >
> > return 0;
> > }
> > -#endif
> >
> > -static UNIVERSAL_DEV_PM_OPS(dw_i2c_dev_pm_ops, dw_i2c_suspend,
> > - dw_i2c_resume, NULL);
> > +static const struct dev_pm_ops dw_i2c_dev_pm_ops = {
> > + .prepare = dw_i2c_prepare,
> > + .complete = dw_i2c_complete,
> > + SET_SYSTEM_SLEEP_PM_OPS(dw_i2c_suspend, dw_i2c_resume)
> > + SET_RUNTIME_PM_OPS(dw_i2c_suspend,
> > + dw_i2c_resume, NULL)
>
> No need to wrap here. It will fit into 80 chars limit.
OOPs, yes. Do I need to send a new version?
>
> Otherwise looks good to me. I also tested this on Braswell and Skylake
> machines where it didn't cause any problems,
>
> Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
>
Thanks for these.
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