Patchwork [3.5.yuz,extended,stable] Patch "usb: musb: am35xx: drop spurious unplugging a device" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Nov. 21, 2012, 5:08 a.m.
Message ID <1353474533-8687-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/200562/
State New
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Herton Ronaldo Krzesinski - Nov. 21, 2012, 5:08 a.m.
This is a note to let you know that I have just added a patch titled

    usb: musb: am35xx: drop spurious unplugging a device

to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.yuz tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From 6168c83048dafcefc3cc22872619b2852ed91be4 Mon Sep 17 00:00:00 2001
From: Stefano Babic <sbabic@denx.de>
Date: Mon, 15 Oct 2012 11:20:22 +0200
Subject: [PATCH] usb: musb: am35xx: drop spurious unplugging a device

commit 6ff1f3d3bd7c69c62ca5773b1b684bce42eff06a upstream.

On AM3517, tx and rx interrupt are detected together with
the disconnect event. This generates a kernel panic in musb_interrupt,
because rx / tx are handled after disconnect.
This issue was seen on a Technexion's TAM3517 SOM. Unplugging a device,
tx / rx interrupts together with disconnect are detected. This brings
to kernel panic like this:

[   68.526153] Unable to handle kernel NULL pointer dereference at virtual address 00000011
[   68.534698] pgd = c0004000
[   68.537536] [00000011] *pgd=00000000
[   68.541351] Internal error: Oops: 17 [#1] ARM
[   68.545928] Modules linked in:
[   68.549163] CPU: 0    Not tainted  (3.6.0-rc5-00020-g9e05905 #178)
[   68.555694] PC is at rxstate+0x8/0xdc
[   68.559539] LR is at musb_interrupt+0x98/0x858
[   68.564239] pc : [<c035cd88>]    lr : [<c035af1c>]    psr: 40000193
[   68.564239] sp : ce83fb40  ip : d0906410  fp : 00000000
[   68.576293] r10: 00000000  r9 : cf3b0e40  r8 : 00000002
[   68.581817] r7 : 00000019  r6 : 00000001  r5 : 00000001  r4 : 000000d4
[   68.588684] r3 : 00000000  r2 : 00000000  r1 : ffffffcc  r0 : cf23c108
[   68.595550] Flags: nZcv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment ke

Note: this behavior is not seen with a USB hub, while it is
easy to reproduce connecting a USB-pen directly to the USB-A of
the board.

Drop tx / rx interrupts if disconnect is detected.

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Felipe Balbi <balbi@ti.com>
Tested-by: Dmitry Lifshitz <lifshitz@compulab.co.il>
Tested-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 drivers/usb/musb/am35x.c |    6 ++++++
 1 file changed, 6 insertions(+)

--
1.7.9.5

Patch

diff --git a/drivers/usb/musb/am35x.c b/drivers/usb/musb/am35x.c
index 9f3eda9..340cff9 100644
--- a/drivers/usb/musb/am35x.c
+++ b/drivers/usb/musb/am35x.c
@@ -311,6 +311,12 @@  static irqreturn_t am35x_musb_interrupt(int irq, void *hci)
 		ret = IRQ_HANDLED;
 	}

+	/* Drop spurious RX and TX if device is disconnected */
+	if (musb->int_usb & MUSB_INTR_DISCONNECT) {
+		musb->int_tx = 0;
+		musb->int_rx = 0;
+	}
+
 	if (musb->int_tx || musb->int_rx || musb->int_usb)
 		ret |= musb_interrupt(musb);