On Mon, 9 Nov 2020 at 16:54, Rafael J. Wysocki <raf...@kernel.org> wrote: > > On Mon, Nov 9, 2020 at 4:50 PM Ulf Hansson <ulf.hans...@linaro.org> wrote: > > > > On Mon, 9 Nov 2020 at 16:20, Rafael J. Wysocki <raf...@kernel.org> wrote: > > > > > > On Mon, Nov 9, 2020 at 4:00 PM Zhang Qilong <zhangqilo...@huawei.com> > > > wrote: > > > > > > > > In many case, we need to check return value of pm_runtime_get_sync, but > > > > it brings a trouble to the usage counter processing. Many callers forget > > > > to decrease the usage counter when it failed. It has been discussed a > > > > lot[0][1]. So we add a function to deal with the usage counter for > > > > better > > > > coding. > > > > > > > > [0]https://lkml.org/lkml/2020/6/14/88 > > > > [1]https://patchwork.ozlabs.org/project/linux-tegra/patch/20200520095148.10995-1-dinghao....@zju.edu.cn/ > > > > Signed-off-by: Zhang Qilong <zhangqilo...@huawei.com> > > > > --- > > > > include/linux/pm_runtime.h | 30 ++++++++++++++++++++++++++++++ > > > > 1 file changed, 30 insertions(+) > > > > > > > > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h > > > > index 4b708f4e8eed..6549ce764400 100644 > > > > --- a/include/linux/pm_runtime.h > > > > +++ b/include/linux/pm_runtime.h > > > > @@ -386,6 +386,36 @@ static inline int pm_runtime_get_sync(struct > > > > device *dev) > > > > return __pm_runtime_resume(dev, RPM_GET_PUT); > > > > } > > > > > > > > +/** > > > > + * pm_runtime_general_get - Bump up usage counter of a device and > > > > resume it. > > > > + * @dev: Target device. > > > > + * > > > > + * Increase runtime PM usage counter of @dev first, and carry out > > > > runtime-resume > > > > + * of it synchronously. If __pm_runtime_resume return negative > > > > value(device is in > > > > + * error state), we to need decrease the usage counter before it > > > > return. If > > > > + * __pm_runtime_resume return positive value, it means the runtime of > > > > device has > > > > + * already been in active state, and we let the new wrapper return > > > > zero instead. > > > > + * > > > > + * The possible return values of this function is zero or negative > > > > value. > > > > + * zero: > > > > + * - it means resume succeeed or runtime of device has already been > > > > active, the > > > > + * runtime PM usage counter of @dev remains incremented. > > > > + * negative: > > > > + * - it means failure and the runtime PM usage counter of @dev has > > > > been balanced. > > > > > > The kerneldoc above is kind of noisy and it is hard to figure out what > > > the helper really does from it. > > > > > > You could basically say something like "Resume @dev synchronously and > > > if that is successful, increment its runtime PM usage counter. Return > > > 0 if the runtime PM usage counter of @dev has been incremented or a > > > negative error code otherwise." > > > > > > > + */ > > > > +static inline int pm_runtime_general_get(struct device *dev) > > > > > > What about pm_runtime_resume_and_get()? > > > > We already have pm_runtime_get_if_active() - so perhaps > > pm_runtime_get_if_suspended() could be an option as well? > > It doesn't work this way, though. > > The "get" happens even if the device has not been suspended.
Yes, that's right - so pm_runtime_resume_and_get() is probably the best we can pick then. Kind regards Uffe
