On Wed, 1 Jan 2020, Guenter Roeck wrote:
On 12/29/19 8:40 AM, Alan Stern wrote:
On Sun, 29 Dec 2019, Guenter Roeck wrote:
On Sat, Dec 28, 2019 at 02:33:01PM -0500, Alan Stern wrote:
Let's try a slightly different approach. What happens with this patch?
Alan Stern
Index: usb-devel/drivers/usb/core/hub.c
--- usb-devel.orig/drivers/usb/core/hub.c +++ usb-devel/drivers/usb/core/hub.c @@ -1065,6 +1065,7 @@ static void hub_activate(struct usb_hub if (type == HUB_INIT) { delay = hub_power_on_good_delay(hub);
hub->power_bits[0] = ~0UL; /* All ports on */ hub_power_on(hub, false); INIT_DELAYED_WORK(&hub->init_work, hub_init_func2); queue_delayed_work(system_power_efficient_wq,That doesn't make a difference - the traceback is still seen with this patch applied.
Can you trace what's going on? Does this code pathway now end up calling ehci_port_power() for each root-hub port, and from there down into the chipidea driver? If not, can you find where it gets sidetracked?
A complete traceback is attached below, so, yes, I think it is safe to say that ehci_port_power() is called unconditionally for each root-hub port on shutdown.
I was really asking about hub activation and powering-up, but you found the answer to that too, so okay.
The only mystery to me was why ehci_port_power() isn't called to enable port power when the port comes up. As it turns out, HCS_PPC(ehci->hcs_params) is false on my simulated hardware, and thus ehci_port_power(..., true) is not called from ehci_hub_control().
Given that, it may well be that the problem is not seen on "real" hardware, at least not with real mcimx7d-sabre hardware, if the hub on that hardware does support power control. To test this idea, I modified qemu to claim hub power control support by setting the "power control support" capability bit. With that, the traceback is gone.
Any suggestion how to proceed ?
Given that HCS_PPC(ehci_hcs_params) is false, I would say that ehci_turn_off_all_ports() shouldn't call ehci_port_power(). You should add that test there. (Although to tell the truth, I'm not really sure we need to test HCS_PPC anywhere...)
Did you check what happens without the patch I sent you? I would like to know if that patch really does make a difference. If we don't send the Set-Port-Feature(power) request during hub activation without the patch then it does need to be merged.
Alan Stern