diff options
| -rw-r--r-- | drivers/usb/host/uhci-hcd.c | 66 |
1 files changed, 34 insertions, 32 deletions
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c index fba99b120588..c8ae199cfbb8 100644 --- a/drivers/usb/host/uhci-hcd.c +++ b/drivers/usb/host/uhci-hcd.c @@ -294,50 +294,50 @@ __acquires(uhci->lock) * and that remote wakeups should be enabled. */ egsm_enable = USBCMD_EGSM; - uhci->RD_enable = 1; int_enable = USBINTR_RESUME; wakeup_enable = 1; - /* In auto-stop mode wakeups must always be detected, but - * Resume-Detect interrupts may be prohibited. (In the absence - * of CONFIG_PM, they are always disallowed.) + /* + * In auto-stop mode, we must be able to detect new connections. + * The user can force us to poll by disabling remote wakeup; + * otherwise we will use the EGSM/RD mechanism. */ if (auto_stop) { if (!device_may_wakeup(&rhdev->dev)) - int_enable = 0; + egsm_enable = int_enable = 0; + } - /* In bus-suspend mode wakeups may be disabled, but if they are - * allowed then so are Resume-Detect interrupts. - */ - } else { #ifdef CONFIG_PM + /* + * In bus-suspend mode, we use the wakeup setting specified + * for the root hub. + */ + else { if (!rhdev->do_remote_wakeup) wakeup_enable = 0; -#endif } +#endif - /* EGSM causes the root hub to echo a 'K' signal (resume) out any - * port which requests a remote wakeup. According to the USB spec, - * every hub is supposed to do this. But if we are ignoring - * remote-wakeup requests anyway then there's no point to it. - * We also shouldn't enable EGSM if it's broken. - */ - if (!wakeup_enable || global_suspend_mode_is_broken(uhci)) - egsm_enable = 0; - - /* If we're ignoring wakeup events then there's no reason to - * enable Resume-Detect interrupts. We also shouldn't enable - * them if they are broken or disallowed. + /* + * UHCI doesn't distinguish between wakeup requests from downstream + * devices and local connect/disconnect events. There's no way to + * enable one without the other; both are controlled by EGSM. Thus + * if wakeups are disallowed then EGSM must be turned off -- in which + * case remote wakeup requests from downstream during system sleep + * will be lost. + * + * In addition, if EGSM is broken then we can't use it. Likewise, + * if Resume-Detect interrupts are broken then we can't use them. * - * This logic may lead us to enabling RD but not EGSM. The UHCI - * spec foolishly says that RD works only when EGSM is on, but - * there's no harm in enabling it anyway -- perhaps some chips - * will implement it! + * Finally, neither EGSM nor RD is useful by itself. Without EGSM, + * the RD status bit will never get set. Without RD, the controller + * won't generate interrupts to tell the system about wakeup events. */ - if (!wakeup_enable || resume_detect_interrupts_are_broken(uhci) || - !int_enable) - uhci->RD_enable = int_enable = 0; + if (!wakeup_enable || global_suspend_mode_is_broken(uhci) || + resume_detect_interrupts_are_broken(uhci)) + egsm_enable = int_enable = 0; + uhci->RD_enable = !!int_enable; uhci_writew(uhci, int_enable, USBINTR); uhci_writew(uhci, egsm_enable | USBCMD_CF, USBCMD); mb(); @@ -364,10 +364,12 @@ __acquires(uhci->lock) uhci->rh_state = new_state; uhci->is_stopped = UHCI_IS_STOPPED; - /* If interrupts don't work and remote wakeup is enabled then - * the suspended root hub needs to be polled. + /* + * If remote wakeup is enabled but either EGSM or RD interrupts + * doesn't work, then we won't get an interrupt when a wakeup event + * occurs. Thus the suspended root hub needs to be polled. */ - if (!int_enable && wakeup_enable) + if (wakeup_enable && (!int_enable || !egsm_enable)) set_bit(HCD_FLAG_POLL_RH, &uhci_to_hcd(uhci)->flags); else clear_bit(HCD_FLAG_POLL_RH, &uhci_to_hcd(uhci)->flags); |