linux-kernel - [PATCH 5.4 041/168] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200428182237.018243861@linuxfoundation.org>
Date:   Tue, 28 Apr 2020 20:23:35 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 041/168] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3

From: Kai-Heng Feng <kai.heng.feng@...onical.com>

[ Upstream commit eb002726fac7cefb98ff39ddb89e150a1c24fe85 ]

The xHCI spec doesn't specify the upper bound of U3 transition time. For
some devices 20ms is not enough, so we need to make sure the link state
is in U3 before further actions.

I've tried to use U3 Entry Capability by setting U3 Entry Enable in
config register, however the port change event for U3 transition
interrupts the system suspend process.

For now let's use the less ideal method by polling PLS.

[use usleep_range(), and shorten the delay time while polling -Mathias]
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Link: https://lore.kernel.org/r/20200312144517.1593-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/usb/host/xhci-hub.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index af92b2576fe91..712cd44f05ace 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1322,7 +1322,16 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			xhci_set_link_state(xhci, ports[wIndex], link_state);
 
 			spin_unlock_irqrestore(&xhci->lock, flags);
-			msleep(20); /* wait device to enter */
+			if (link_state == USB_SS_PORT_LS_U3) {
+				int retries = 16;
+
+				while (retries--) {
+					usleep_range(4000, 8000);
+					temp = readl(ports[wIndex]->addr);
+					if ((temp & PORT_PLS_MASK) == XDEV_U3)
+						break;
+				}
+			}
 			spin_lock_irqsave(&xhci->lock, flags);
 
 			temp = readl(ports[wIndex]->addr);
-- 
2.20.1