Hi Alan,
When I try to optimize system resume time, I find bus resume routine
cost much time (> 20ms), even there is no device at any ports.
Let's take ehci bus resume as an example.
1. At ehci_bus_resume
/* Some controller/firmware combinations need a delay during which
* they set up the port statuses. See Bugzilla #8190. */
spin_unlock_irq(&ehci->lock);
msleep(8);
spin_lock_irq(&ehci->lock);
Is it possible to add condition?
2. At hcd_bus_resume
if (status == 0) {
/* TRSMRCY = 10 msec */
msleep(10);
This 10ms delay is needed when the device is connected and CONFIG_USB_SUSPEND
is not defined, can we add condition like:
if (status == 0) {
#ifndef CONFIG_USB_SUSPEND
if (no_device_on_port)
/* TRSMRCY = 10 msec */
msleep(10);
#endif
For the no_device_on_port, it needs to add flag at struct usb_hcd.
--
Best Regards,
Peter Chen
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