On Thu, 14 Nov 2013, Nishanth Menon wrote: > OMAP device hooks around suspend|resume_noirq ensures that hwmod > devices are forced to idle using omap_device_idle/enable as part of > the last stage of suspend activity. > > For a device such as i2c who uses autosuspend, it is possible to enter > the suspend path with dev->power.runtime_status = RPM_ACTIVE. > > As part of the suspend flow, the generic runtime logic would increment > it's dev->power.disable_depth to 1. This should prevent further > pm_runtime_get_sync from succeeding once the runtime_status has been > set to RPM_SUSPENDED. > > Now, as part of the suspend_noirq handler in omap_device, we force the > following: if the device status is !suspended, we force the device > to idle using omap_device_idle (clocks are cut etc..). This ensures > that from a hardware perspective, the device is "suspended". However, > runtime_status is left to be active. > > *if* an operation is attempted after this point to > pm_runtime_get_sync, runtime framework depends on runtime_status to > indicate accurately the device status, and since it sees it to be > ACTIVE, it assumes the module is functional and returns a non-error > value. As a result the user will see pm_runtime_get succeed, however a > register access will crash due to the lack of clocks. > > To prevent this from happening, we should ensure that runtime_status > exactly indicates the device status. As a result of this change > any further calls to pm_runtime_get* would return -EACCES (since > disable_depth is 1). On resume, we restore the clocks and runtime > status exactly as we suspended with. These operations are not expected > to fail as we update the states after the core runtime framework has > suspended itself and restore before the core runtime framework has > resumed. > > Reported-by: J Keerthy <j-keerthy@xxxxxx> > Signed-off-by: Nishanth Menon <nm@xxxxxx> > Acked-by: Rajendra Nayak <rnayak@xxxxxx> > Acked-by: Kevin Hilman <khilman@xxxxxxxxxx> Looks reasonable to me. Looks like this should be considered for -stable - Nishanth, what do you think? Tony or Kevin, do you want to take this one, or want me to? - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
