RE: imx-uart DMA transaction error leading to OOPS on 4.14.95

[Robin Gong <yibin.gong@nxp.com>]

Sorry, please ignore my information, sdma didn't use virt-dma on 4.14....

> -----Original Message-----
> From: Robin Gong
> Sent: 2019年2月12日 11:42
> To: 'Petr Štetiar' <ynezz@true.cz>; Vinod Koul <vkoul@kernel.org>
> Cc: Fabio Estevam <festevam@gmail.com>; Lucas Stach
> <l.stach@pengutronix.de>; dmaengine@vger.kernel.org;
> linux-arm-kernel@lists.infradead.org
> Subject: RE: imx-uart DMA transaction error leading to OOPS on 4.14.95
> 
> Hi Petr,
> 	Could you check the below patch set which is not in v4.14.98?
> https://patchwork.kernel.org/patch/10057791/
> 
> > -----Original Message-----
> > From: Petr Štetiar <ynezz@true.cz>
> > Sent: 2019年2月11日 17:28
> > To: Vinod Koul <vkoul@kernel.org>
> > Cc: Fabio Estevam <festevam@gmail.com>; Lucas Stach
> > <l.stach@pengutronix.de>; Robin Gong <yibin.gong@nxp.com>;
> > dmaengine@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> > Subject: Re: imx-uart DMA transaction error leading to OOPS on 4.14.95
> >
> > Vinod Koul <vkoul@kernel.org> [2019-02-11 17:36:16]:
> >
> > Hi,
> >
> > > > I've just encountered following OOPS on 4.14.95:
> > > >
> > > >   imx-uart 21f0000.serial: DMA transaction error.
> > >
> > > Do you see this on mainline as well, bit of fixes went into this
> > > driver recently...
> >
> > I've hit it only once on 4.14 so far, it's quite hard to reproduce it,
> > so no big deal, but I've just thought, that someone might be
> > interested. Once I find some way to reproduce it, I'll try to test it on some
> recent kernel.
> >
> > BTW, any idea which of those fixes might be related to this Oops and
> > might be worth backporting to 4.14?
> >
> > > >   Unable to handle kernel paging request at virtual address a0ee501a
> > > >   pgd = 9d7d4000
> > > >   [a0ee501a] *pgd=2d8d1811, *pte=00000000, *ppte=00000000
> > > >   Internal error: Oops: 7 [#1] SMP ARM
> > ...
> > > >   CPU: 0 PID: 2536 Comm: sh Not tainted 4.14.95 #0
> > > >   Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> > > >   task: 9f67ca00 task.stack: 9b642000
> > > >   PC is at sdma_int_handler+0x7c/0x17c
> > >
> > > So we get an interrupt while doing shutdown.. That is interesting..
> >
> > I'm using serial console on ttymxc0 (115200,8n1) and UHF RFID reader
> > on
> > ttymxc3(921600,8n1) which is sending reports asynchronously and it was
> > active during the shutdown as I was testing new hardware revision during
> that time.
> >
> > > >   PC is at sdma_int_handler+0x7c/0x17c
> > > >   LR is at console_unlock+0x480/0x4ec
> >
> > I'm not sure how to interpret this, but is it possible, that there
> > might be some race while sdma_int_handler could be processing
> > interrupt on ttymxc3 while the system is doing some console output on
> > ttymxc0? I just use the console for observation, so I wasn't typing or
> > otherwise utilizing it, so probably no reason for interrupt from ttymxc0.
> >
> > -- ynezz
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