I used kgdb. Is it ok? channel appeared to be 0x0: (gdb) continue Continuing. [Switching to Thread 315] Breakpoint 1, cppi41_dma_channel_program (channel=0x0, packet_sz=960, mode=0 '\000', dma_addr=2609136576, len=960) at ../drivers/usb/musb/musb_cppi41.c:481 481 { (gdb) bt #0 cppi41_dma_channel_program (channel=0x0, packet_sz=960, mode=0 '\000', dma_addr=2609136576, len=960) at ../drivers/usb/musb/musb_cppi41.c:481 #1 0xbf251570 in musb_rx_dma_iso_cppi41 (len=<optimized out>, urb=<optimized out>, qh=<optimized out>, hw_ep=<optimized out>, dma=<optimized out>) at ../drivers/usb/musb/musb_host.c:1569 #2 musb_rx_dma_inventra_cppi41 (len=<optimized out>, urb=<optimized out>, qh=<optimized out>, hw_ep=<optimized out>, dma=<optimized out>) at ../drivers/usb/musb/musb_host.c:1652 #3 musb_host_rx (musb=0xdb3e0010, epnum=<optimized out>) at ../drivers/usb/musb/musb_host.c:1969 #4 0xbf249fb4 in musb_dma_completion (musb=<optimized out>, epnum=<optimized out>, transmit=<optimized out>) at ../drivers/usb/musb/musb_core.c:1693 #5 0xbf258b10 in cppi41_trans_done (cppi41_channel=0xd914c3bc) at ../drivers/usb/musb/musb_cppi41.c:148 #6 0xbf258c1c in cppi41_dma_callback (private_data=<optimized out>) at ../drivers/usb/musb/musb_cppi41.c:286 #7 0xbf229f38 in ?? () Backtrace stopped: previous frame identical to this frame (corrupt stack?) 2016-05-20 23:10 GMT+03:00 Bin Liu <b-liu@xxxxxx>: > Hi, > > On Fri, May 20, 2016 at 04:32:06PM +0300, Matwey V. Kornilov wrote: >> 2016-05-20 16:19 GMT+03:00 <matwey@xxxxxxxxxx>: >> > Hello, >> > >> > I am running 4.6-rc3 on BealgeBone Black and when I try to interract >> > with pwc webcam attached to usb port the following kernel panic >> > happening. >> >> Please note, that the same is happening with 4.6.0 release. > > Please apply the following patch and reproduce the oops, I'd like to > check if the oops is caused by NULL of hw_ep->in_qh. > > Regards, > -Bin. > > ---8<------- > diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c > index e499b86..3492c6e 100644 > --- a/drivers/usb/musb/musb_cppi41.c > +++ b/drivers/usb/musb/musb_cppi41.c > @@ -489,8 +489,11 @@ static int cppi41_dma_channel_program(struct dma_channel *channel, > if (is_host_active(cppi41_channel->controller->musb)) { > if (cppi41_channel->is_tx) > hb_mult = cppi41_channel->hw_ep->out_qh->hb_mult; > - else > + else { > + if (!cppi41_channel->hw_ep->in_qh) > + dev_err(NULL, "->in_qh is NULL\n"); > hb_mult = cppi41_channel->hw_ep->in_qh->hb_mult; > + } > } > > channel->status = MUSB_DMA_STATUS_BUSY; > -- With best regards, Matwey V. Kornilov. Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia 119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html