Hi, * Ulf Hansson <ulf.hansson@xxxxxxxxxx> [160202 02:43]: > > For the omap_hsmmc and likely also other omap drivers, which needs more > than one attempt to ->probe() (returning -EPROBE_DEFER), this commit > causes a regression at the PM domain level (omap hwmod). > > The reason is that the drivers don't put back the device into low power > state while bailing out in ->probe to return -EPROBE_DEFER. This leads to > that pm_runtime_reinit() in driver core, is re-initializing the runtime PM > status from RPM_ACTIVE to RPM_SUSPENDED. Yup, that's the bug here. It seems that we never call the runtime_suspend callback at the end of a first failed device driver probe if the driver has set pm_runtime_use_autosuspend. Only rpm_idle runtime_idle callback gets called. So the device stays on. This does not happen if pm_runtime_dont_use_autosuspend() is added to the end of the device driver probe before pm_runtime_put_sync(). > The next ->probe() attempt then triggers the ->runtime_resume() callback > to be invoked, which means this happens two times in a row. At the PM > domain level (omap hwmod) this is being treated as an error and thus the > runtime PM status of the device isn't correctly synchronized with the > runtime PM core. That's a valid error though, let's not remove it. The reason why we call runtime_resume() twice is because runtime_suspend callback never gets called like I explain above. > In the end, ->probe() anyway succeeds (as the driver don't checks the > error code from the runtime PM APIs), but results in that the PM domain > always stays powered on. This because of the runtime PM core believes the > device is RPM_SUSPENDED. FYI, the following allows runtime_suspend callback to get called at the end of a failed driver probe so the hardware state matches the PM runtime state. Need to debug more. Regards, Tony 8< ------------ --- a/drivers/mmc/host/omap_hsmmc.c +++ b/drivers/mmc/host/omap_hsmmc.c @@ -2232,6 +2232,7 @@ err_irq: dma_release_channel(host->tx_chan); if (host->rx_chan) dma_release_channel(host->rx_chan); + pm_runtime_dont_use_autosuspend(host->dev); pm_runtime_put_sync(host->dev); pm_runtime_disable(host->dev); if (host->dbclk) -- 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
