This is a note to let you know that I've just added the patch titled
xhci: Add grace period after xHC start to prevent premature runtime suspend.
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xhci-add-grace-period-after-xhc-start-to-prevent-premature-runtime-suspend.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 33e321586e37b642ad10594b9ef25a613555cd08 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Date: Thu, 25 Aug 2022 18:08:39 +0300
Subject: xhci: Add grace period after xHC start to prevent premature runtime suspend.
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
commit 33e321586e37b642ad10594b9ef25a613555cd08 upstream.
After xHC controller is started, either in probe or resume, it can take
a while before any of the connected usb devices are visible to the roothub
due to link training.
It's possible xhci driver loads, sees no acivity and suspends the host
before the USB device is visible.
In one testcase with a hotplugged xHC controller the host finally detected
the connected USB device and generated a wake 500ms after host initial
start.
If hosts didn't suspend the device duringe training it probablty wouldn't
take up to 500ms to detect it, but looking at specs reveal USB3 link
training has a couple long timeout values, such as 120ms
RxDetectQuietTimeout, and 360ms PollingLFPSTimeout.
So Add a 500ms grace period that keeps polling the roothub for 500ms after
start, preventing runtime suspend until USB devices are detected.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220825150840.132216-3-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci-hub.c | 11 +++++++++++
drivers/usb/host/xhci.c | 4 +++-
drivers/usb/host/xhci.h | 2 +-
3 files changed, 15 insertions(+), 2 deletions(-)
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1561,6 +1561,17 @@ int xhci_hub_status_data(struct usb_hcd
status = bus_state->resuming_ports;
+ /*
+ * SS devices are only visible to roothub after link training completes.
+ * Keep polling roothubs for a grace period after xHC start
+ */
+ if (xhci->run_graceperiod) {
+ if (time_before(jiffies, xhci->run_graceperiod))
+ status = 1;
+ else
+ xhci->run_graceperiod = 0;
+ }
+
mask = PORT_CSC | PORT_PEC | PORT_OCC | PORT_PLC | PORT_WRC | PORT_CEC;
/* For each port, did anything change? If so, set that bit in buf. */
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -149,9 +149,11 @@ int xhci_start(struct xhci_hcd *xhci)
xhci_err(xhci, "Host took too long to start, "
"waited %u microseconds.\n",
XHCI_MAX_HALT_USEC);
- if (!ret)
+ if (!ret) {
/* clear state flags. Including dying, halted or removing */
xhci->xhc_state = 0;
+ xhci->run_graceperiod = jiffies + msecs_to_jiffies(500);
+ }
return ret;
}
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1816,7 +1816,7 @@ struct xhci_hcd {
/* Host controller watchdog timer structures */
unsigned int xhc_state;
-
+ unsigned long run_graceperiod;
u32 command;
struct s3_save s3;
/* Host controller is dying - not responding to commands. "I'm not dead yet!"
Patches currently in stable-queue which might be from mathias.nyman@xxxxxxxxxxxxxxx are
queue-5.10/xhci-add-grace-period-after-xhc-start-to-prevent-premature-runtime-suspend.patch
queue-5.10/revert-xhci-turn-off-port-power-in-shutdown.patch
