linux-kernel - Re: [PATCHv2] musb_host: fix lockup on rxcsr_h

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Date:	Wed, 4 May 2016 14:17:15 -0500
From:	Bin Liu <b-liu@...com>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
CC:	Yegor Yefremov <yegorslists@...glemail.com>,
	Maxim Uvarov <muvarov@...il.com>,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-usb <linux-usb@...r.kernel.org>,
	Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCHv2] musb_host: fix lockup on rxcsr_h_error

Hi,

On Wed, May 04, 2016 at 10:02:16PM +0300, Sergei Shtylyov wrote:
> Hello.
> 
> On 05/04/2016 09:56 PM, Bin Liu wrote:
> 
> >>>>>>>>yes, it also works with that reset and go to finish:
> >>>>>>>>
> >>>>>>>>diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> >>>>>>>>index c3d5fc9..8cd98e7 100644
> >>>>>>>>--- a/drivers/usb/musb/musb_host.c
> >>>>>>>>+++ b/drivers/usb/musb/musb_host.c
> >>>>>>>>@@ -1599,6 +1599,10 @@ void musb_host_rx(struct musb *musb, u8 epnum)
> >>>>>>>>                 status = -EPROTO;
> >>>>>>>>                 musb_writeb(epio, MUSB_RXINTERVAL, 0);
> >>>>>>>>
> >>>>>>>>+               rx_csr &= ~MUSB_RXCSR_H_ERROR;
> >>>>>>>>+               musb_writew(epio, MUSB_RXCSR, rx_csr);
> >>>>>>>>+
> >>>>>>>>+               goto finish;
> >>>>>>>>         } else if (rx_csr & MUSB_RXCSR_DATAERROR) {
> >>>>>>>>
> >>>>>>>>                 if (USB_ENDPOINT_XFER_ISOC != qh->type) {
> >>>>>>>>
> >>>>>>>
> >>>>>>>Thanks for testing it.
> >>>>>>
> >>>>>>Have tested your patch and now both FT4232 and Huawei don't freeze on removal.
> >>>>>>
> >>>>>>Bin, Max thanks for fixing this issue.
> >>>>>>
> >>>>>>Tested-by: Yegor Yefremov <yegorslists@...glemail.com>
> >>>>>
> >>>>>Thanks for testing.
> >>>>>
> >>>>>Can you please test the patch [1] instead? I'd like to use it as the
> >>>>>fix.
> >>>>>
> >>>>>[1] http://marc.info/?l=linux-usb&m=146222355213935&w=2
> >>>>
> >>>>The patch behaves the same as the previous one.
> >>>>
> >>>>Kernel: 4.6-rc6
> >>>
> >>>Thanks for testing. I will add your Tested-by.
> >>
> >>If you'll resend this patch, it would be good to add it to stable
> >>kernels. I've tested 3.18.32 and it fixes the error too.
> 
> >Thanks for testing.
> >
> >My plan is to not rush it into stable, but let it sit in v4.7 for a
> >while first.
> 
>    Are you serious? Fixing interrupt storm due to not cleared
> interrupt bit will only be done in 4.7?

Well, I am new to maintianer's role, and thought there is only one week
away to v4.7 merge window, there is no big difference to let this patch
get into v4.7-rc1. If getting the fix into upstream as soon as possible
is important, I will send it for 4.6-rc7.

BTY, the issue is not because of not clearing interrupt bit, but the hub
has no chance to report the disconnect event, which causes the
controller keeps generating the interrupt for every new rx urb.

Regards,
-Bin.

> 
> >Regards,
> >-Bin.
> 
> MBR, Sergei
>