On 9.6.2022 18.08, Evan Green wrote:
On Thu, Jun 9, 2022 at 12:58 AM Mathias Nyman
<mathias.nyman@xxxxxxxxxxxxxxx> wrote:
On 8.6.2022 16.43, Alan Stern wrote:
On Wed, Jun 08, 2022 at 02:47:22PM +0300, Mathias Nyman wrote:
On 8.6.2022 11.19, Oliver Neukum wrote:
On 07.06.22 15:58, Mathias Nyman wrote:
Hi,
In shutdown (S5), with xHCI as host, this can be solved fairly easily
by turning off roothub port power in the .shutdown path.
That would suck for the people who charge their phone from their
computer.
Good point.
My guess is that xHC port power bits won't actually turn off VBus for those
Sleep-and-charge, or Always-on ports.
VBus is allowed to be on even if port is in power-off state, but usb link state
should be forced to ss.Disabled from other states, like U3.
Need to try it out, it's possible this turns off VBus for some usb-A ports
on some older systems that earlier (accidentally?) supplied VBus on
"normal" ports after shutdown.
How about turning off port power _only_ in the shutdown or unbind path,
and setting the port link states to ss.Disabled in the poweroff or
poweroff_noirq stage of hibernation (if wakeup is disabled)? Would that
solve the problem of the firmware needing to time out on reboot?
That would be optimal, but unfortunately xHCI doesn't support setting link
state directly to ss.Disabled. Only way is to clear port power (PP) bit.
To avoid turning off VBus in hibernate we could limit port power bit clearing
to xHC hosts that don't have the Port Power Control (PPC) capability flag.
We know these xHC hosts don't control power switches, and clearing PP won't turn
off VBus (xhci 5.4.8, PORTRSC)
This could be a solution for some hosts, but probably not cover all.
Not sure if the hardware this was reported on has PPC flag set.
It appears it does not, HCCPARAMS1 for both USB controllers seems to
be 0x20007fc1 (missing bit 3). You can check my work in case I made an
error here: https://pastebin.com/9raZc63N
-Evan
Thanks, good to know.
So if disabling ports in hibernate doesn't work then we could turn off port power for
hosts with PPC==0. It should at least solve the issue for this particular system,
and not change current VBus policy in hibernate.
-Mathias
