linux-kernel - [PATCH AUTOSEL 4.4 04/21] usb: handle warm-reset port requests on hub resume

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Message-Id: <20191018221007.10851-4-sashal@kernel.org>
Date:   Fri, 18 Oct 2019 18:09:50 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jan-Marek Glogowski <glogow@...home.de>,
        Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>, linux-usb@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 04/21] usb: handle warm-reset port requests on hub resume

From: Jan-Marek Glogowski <glogow@...home.de>

[ Upstream commit 4fdc1790e6a9ef22399c6bc6e63b80f4609f3b7e ]

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@...home.de>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 5c274c5440da4..11881c5a1fb0c 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -102,6 +102,8 @@ 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)
 {
@@ -1092,6 +1094,11 @@ 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
-- 
2.20.1