Re: [OOPS] cppi41_dma_channel_program: Unable to handle kernel NULL pointer dereference

[Bin Liu <b-liu-l0cyMroinI0@public.gmane.org>]

Hi,

On Sat, May 21, 2016 at 10:04:48PM +0300, Matwey V. Kornilov wrote:
> 2016-05-21 20:50 GMT+03:00 Matwey V. Kornilov <matwey-TTlVxmypnbovJsYlp49lxw@public.gmane.org>:
> > 2016-05-21 6:13 GMT+03:00 Bin Liu <binmlist-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> >> Hi,
> >>
> >> On Fri, May 20, 2016 at 4:20 PM, Matwey V. Kornilov <matwey-TTlVxmypnbovJsYlp49lxw@public.gmane.org> wrote:
> >>> 2016-05-21 0:12 GMT+03:00 Bin Liu <b-liu-l0cyMroinI0@public.gmane.org>:
> >>>> Hi,
> >>>>
> >>>> On Sat, May 21, 2016 at 12:05:06AM +0300, Matwey V. Kornilov wrote:
> >>>>> By the way, is it ok that function musb_rx_dma_iso_cppi41 uses
> >>>>> hw_ep->tx_channel? I would suppose that it should use rx_channel
> >>>>> instead.
> >>>>
> >>>> I just got here, and am wondering the same. But the question is why just
> >>>> your case hit the problem. I will try to look at it more next week.
> >>>>
> >>>> I had an impression the linux-usb@ has a discussion before about
> >>>> rx/tx-channel messing up, will have to look it up.
> >>>>
> >>>
> >>> Thank you.
> >>> If you need additional info, I can use kgdb with this issue.
> >>
> >> After reviewed the code, it must be hw_ep->rx_channel instead. It is likely a
> >> bug caused by commit 069a3fd (usb: musb: Remove ifdefs for musb_host_rx
> >> in musb_host.c part1). Please test with the following patch.
> >>
> >
> > I've just tested this patch. Indeed, it helps to avoid kernel panic.
> > Now, I can interact with my webcam and watch video-stream in  xawtv.
> > It would be great if the patch could become a part of 4.6.x stable tree.
> >
> 
> Hm, the following string appeared one time during my testing:
> 
> [  867.017179] musb_host_rx 1925: RX14 dma busy, csr 2020

This seems to be a different issue. Does your webcam still functional
after the log shows up?

Regards,
-Bin.
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