On Tue, 2021-01-05 at 09:07 +0800, Can Guo wrote: > On 2021-01-05 04:05, Bean Huo wrote: > > On Sat, 2021-01-02 at 05:59 -0800, Can Guo wrote: > > > + * @shutting_down: flag to check if shutdown has been invoked > > > > I am not much sure if this flag is need, since once PM going in > > shutdown path, what will be returnded by pm_runtime_get_sync()? > > > > If pm_runtime_get_sync() will fail, just check its return. > > > > That depends. During/after shutdown, for UFS's case only, > pm_runtime_get_sync(hba->dev) will most likely return 0, > because it is already RUNTIME_ACTIVE, pm_runtime_get_sync() > will directly return 0... meaning you cannot count on it. > > Check Stanley's change - > https://lore.kernel.org/patchwork/patch/1341389/ > > Can Guo. Can, Thanks for pointing out that. Based on my understanding, that patch is redundent. maybe I misundestood Linux shutdown sequence. I checked the shutdown flow: 1. Set the "system_state" variable 2. Disable usermod to ensure that no user from userspace can start a request 3. device_shutdown() So, userspace thread can not start a request to trigger runtime resume(pm_runtime_get_sync) after step 2. also, no need to add that flag to checkup if shutdwon is running, maybe it is better to check variable system_state: if (system_state == SYSTEM_POWER_OFF || system_state == SYSTEM_HALT || system_state == SYSTEM_RESTART) //shutdown start I still hope Rafael or someone else can confirm that if pm_runtime_get_sync() will really return ok in shutdown flow. thanks, Bean > > > Hi Rafael > > would you please help us confirm this? > > > > thanks, > > Bean
