On Wed, Sep 16, 2015 at 06:22:27PM +0100, Felipe Tonello wrote:
> Hi Estevam,
>
> On Tue, Sep 15, 2015 at 5:09 AM, Fabio Estevam <festevam@xxxxxxxxx> wrote:
> > On Thu, Sep 10, 2015 at 6:47 AM, Felipe Tonello <eu@xxxxxxxxxxxxxxxxx> wrote:
> >> Hi,
> >>
> >> I have the following setup:
> >>
> >> DSP (read sensors and read/send MIDI) <- UART -> SOC (imx6) <- USB
> >> MIDI GADGET -> HOST
> >>
> >> When the throughput from the DSP is high, thus causing the throughput
> >> on the USB to be high as well, I get a Kernel Panic saying to increase
> >> the coherent_pool. I've used some crazy sizes like 1M, 4M and even 8M.
> >> Obviously when I increase, it takes longer to crash but it still
> >> crashes.
> >>
> >> I am using linux-fsl 3.14.28.
> >
> > Please test it with 4.2 or 4.3-rc1 kernel.
>
> I tested on 4.2 and still crashes. Same thing. But it doesn't say
> about the dma any longer.
then this is a different problem with v4.2, right. Which UDC controller is
your board using ? Who's the maintainer for that ?
> [ 148.712916] Unable to handle kernel NULL pointer dereference at
> virtual address 00000000
> [ 148.721135] pgd = 80004000
> [ 148.723859] [00000000] *pgd=00000000
> [ 148.727475] Internal error: Oops: 817 [#1] PREEMPT SMP ARM
> [ 148.732975] Modules linked in: snd_seq_midi snd_seq_dummy
> snd_seq_midi_event snd_seq usb_f_midi snd_rawmidi snd_seq_device
> g_midi libcomposite configfs snd_soc_fsl_ssi ime
> [ 148.761694] CPU: 0 PID: 3 Comm: ksoftirqd/0 Not tainted
> 4.2.0-mx6-seaboard-dirty #1
> [ 148.769364] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> [ 148.775909] task: ee070980 ti: ee086000 task.ti: ee086000
> [ 148.781342] PC is at _ep_queue.isra.18+0x178/0x480
care to use addr2line or gdb to figure out exactly where this is ?
gdb vmlinux followed by l *(_ep_queue.isra.18 + 0x178) should tell you
which line cause the NULL pointer dereference.
>
> gdb shows this calls:
> (gdb) list *(ep_queue+0x44)
can you check the other one which I mentioned above ?
> 0x803caae4 is in ep_queue (../include/linux/spinlock.h:372).
> 367 raw_spin_unlock_irq(&lock->rlock);
> 368 }
> 369
> 370 static inline void spin_unlock_irqrestore(spinlock_t *lock,
> unsigned long flags)
> 371 {
> 372 raw_spin_unlock_irqrestore(&lock->rlock, flags);
> 373 }
> 374
> 375 static inline int spin_trylock_bh(spinlock_t *lock)
> 376 {
> (gdb) list *(_ep_queue)
> 0x803c9790 is in _ep_queue (../drivers/usb/chipidea/udc.c:756).
> 751 /**
> 752 * _ep_queue: queues (submits) an I/O request to an endpoint
> 753 *
> 754 * Caller must hold lock
> 755 */
> 756 static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
> 757 gfp_t __maybe_unused gfp_flags)
> 758 {
> 759 struct ci_hw_ep *hwep = container_of(ep, struct
> ci_hw_ep, ep);
> 760 struct ci_hw_req *hwreq = container_of(req, struct
> ci_hw_req, req);
>
> Any ideas on how to debug it?
you gotta figure out where is this NULL pointer coming from, then
find a way to fix it. Considering you're using chipidea, it would
be a good idea to Cc Peter, who's the chipidea maintainer.
--
balbi
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