On Mon, Nov 9, 2020 at 2:24 PM zhangqilong <zhangqilo...@huawei.com> wrote: > > Hi > > > > On Mon, Nov 9, 2020 at 9:05 AM 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/202005200951 > > > 48.10995-1-dinghao....@zju.edu.cn/ > > > Signed-off-by: Zhang Qilong <zhangqilo...@huawei.com> > > > --- > > > include/linux/pm_runtime.h | 32 ++++++++++++++++++++++++++++++++ > > > 1 file changed, 32 insertions(+) > > > > > > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h > > > index 4b708f4e8eed..2b0af5b1dffd 100644 > > > --- a/include/linux/pm_runtime.h > > > +++ b/include/linux/pm_runtime.h > > > @@ -386,6 +386,38 @@ static inline int pm_runtime_get_sync(struct device > > *dev) > > > return __pm_runtime_resume(dev, RPM_GET_PUT); } > > > > > > +/** > > > + * gene_pm_runtime_get_sync - Bump up usage counter of a device and > > resume it. > > > + * @dev: Target device. > > > > The force argument is not documented. > > (1) Good catch, I will add it in next version. > > > > > > + * > > > + * 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) or return positive value(the runtime of device is > > > + already active) > > > + * with force is true, it need decrease the usage counter of the > > > + device when > > > + * return. > > > + * > > > + * The possible return values of this function is zero or negative value. > > > + * zero: > > > + * - it means success and the status will store the resume operation > > status > > > + * if needed, the runtime PM usage counter of @dev remains > > incremented. > > > + * negative: > > > + * - it means failure and the runtime PM usage counter of @dev has > > been > > > + * decreased. > > > + * positive: > > > + * - it means the runtime of the device is already active before > > > that. If > > > + * caller set force to true, we still need to decrease the usage > > counter. > > > > Why is this needed? > > (2) If caller set force, it means caller will return even the device has > already been active > (__pm_runtime_resume return positive value) after calling > gene_pm_runtime_get_sync, > we still need to decrease the usage count.
But who needs this? I don't think that it is a good idea to complicate the API this way.
