linux-kernel - [PATCH] Revert "USB: quirks: ignore remote wake-up on Fibocom L850-GL LTE modem"

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Message-Id: <20210721092516.2775971-1-vpalatin@chromium.org>
Date:   Wed, 21 Jul 2021 11:25:16 +0200
From:   Vincent Palatin <vpalatin@...omium.org>
To:     linux-usb@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        Vincent Palatin <vpalatin@...omium.org>
Subject: [PATCH] Revert "USB: quirks: ignore remote wake-up on Fibocom L850-GL LTE modem"

This reverts commit 0bd860493f81eb2a46173f6f5e44cc38331c8dbd.

While the patch was working as stated,ie preventing the L850-GL LTE modem
from crashing on some U3 wake-ups due to a race condition between the
host wake-up and the modem-side wake-up, when using the MBIM interface,
this would force disabling the USB runtime PM on the device.

The increased power consumption is significant for LTE laptops,
and given that with decently recent modem firmwares, when the modem hits
the bug, it automatically recovers (ie it drops from the bus, but
automatically re-enumerates after less than half a second, rather than being
stuck until a power cycle as it was doing with ancient firmware), for
most people, the trade-off now seems in favor of re-enabling it by
default.

For people with access to the platform code, the bug can also be worked-around
successfully by changing the USB3 LFPM polling off-time for the XHCI
controller in the BIOS code.

Signed-off-by: Vincent Palatin <vpalatin@...omium.org>
---
 drivers/usb/core/quirks.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index 6114cf83bb44..8239fe7129dd 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -501,10 +501,6 @@ static const struct usb_device_id usb_quirk_list[] = {
 	/* DJI CineSSD */
 	{ USB_DEVICE(0x2ca3, 0x0031), .driver_info = USB_QUIRK_NO_LPM },

-	/* Fibocom L850-GL LTE Modem */
-	{ USB_DEVICE(0x2cb7, 0x0007), .driver_info =
-			USB_QUIRK_IGNORE_REMOTE_WAKEUP },
-
 	/* INTEL VALUE SSD */
 	{ USB_DEVICE(0x8086, 0xf1a5), .driver_info = USB_QUIRK_RESET_RESUME },

-- 
2.32.0.402.g57bb445576-goog