On 10/04/12 14:34, Stefano Babic wrote:
> 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 with Technexion's TAM3517 SOM. Unplugging a device,
> tx / rx interrupts togetehr 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 connectict a USB-poen directly to the USB-A of
> the board.
>
> Drop tx / rx interrupts if disconnect is detected.
>
> Signed-off-by: Stefano Babic <sbabic@xxxxxxx>
> CC: Felipe Balbi <balbi@xxxxxx>
Tested-by: Dmitry Lifshitz <lifshitz@xxxxxxxxxxxxxx>
Tested-by: Igor Grinberg <grinberg@xxxxxxxxxxxxxx>
This patch fixes a real bug and probably has been present for some
time already, so I think:
Cc: stable@xxxxxxxxxxxxxxx
would be appropriate here.
Thanks!
> ---
>
> drivers/usb/musb/am35x.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/usb/musb/am35x.c b/drivers/usb/musb/am35x.c
> index b9b165b..b5c813a 100644
> --- a/drivers/usb/musb/am35x.c
> +++ b/drivers/usb/musb/am35x.c
> @@ -312,6 +312,12 @@ 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);
>
--
Regards,
Igor.
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