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.
Signed-off-by: Jan-Marek Glogowski <glogow@xxxxxxxxxx>
---
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
--
2.1.4
