On Fri, Feb 01, 2019 at 01:52:31PM +0100, Jan-Marek Glogowski wrote: > On plug-in of my USB-C device, its USB_SS_PORT_LS_SS_INACTIVE > link state bit is set. Greping all the kernel for this bit shows > that the port status requests a warm-reset this way. > > This just happens, if its the only device on the root hub, the hub > therefore resumes and the HCDs status_urb isn't yet available. > If a warm-reset request is detected, this sets the hubs event_bits, > which will prevent any auto-suspend and allows the hubs workqueue > to warm-reset the port later in port_event. Hi - just a heads-up while we continue to debug - we've received a regression report in Ubuntu after pulling this in from stable. It was bisected down to this commit and still reproducible w/ 5.5-rc2: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1856608 -dann > Signed-off-by: Jan-Marek Glogowski <glogow@xxxxxxxxxx> > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > --- > > The original thread is "USB-C storage device not detected on USB 3.1 Gen 2 > host when plugged in after boot". A different patch, suggested by Mathias > Nyman, didn't work for me. This patch was just rebased on usb-next, but not > re-tested. Original tests are based on 5.0-rc. > > v1: This always warm-resets the ports in hub_activate, independent of the > "enum hub_activation_type". Just had a single device to test. > > v2: I had the idea about the working device, if there is already a device > connected to the hub and that a resume only on "type == HUB_RESUME" should > be sufficient. This still works for me, but I didn't follow all the > hub_activate callers everywhere and I'm definitly still missing a lot of > knowledge about USB stuff. There is also HUB_RESET_RESUME with a slightly > different code path. I don't know how to trigger this. > > v3: code unchanged to v2. > > v4: instead of handling the warm-reset directly from hub_activate by calling > hub_port_reset, this defers the reset by setting the hubs event_bits of the > port. > > --- > drivers/usb/core/hub.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index bb0830c..8d4631c 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -108,6 +108,8 @@ EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem); > static void hub_release(struct kref *kref); > static int usb_reset_and_verify_device(struct usb_device *udev); > static int hub_port_disable(struct usb_hub *hub, int port1, int set_state); > +static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1, > + u16 portstatus); > > static inline char *portspeed(struct usb_hub *hub, int portstatus) > { > @@ -1137,6 +1139,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) > USB_PORT_FEAT_ENABLE); > } > > + /* Make sure a warm-reset request is handled by port_event */ > + if (type == HUB_RESUME && > + hub_port_warm_reset_required(hub, port1, portstatus)) > + set_bit(port1, hub->event_bits); > + > /* > * Add debounce if USB3 link is in polling/link training state. > * Link will automatically transition to Enabled state after
