linux-kernel - Re: [PATCH v3 0/6] add virt-dma support for imx-sdma

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Date:   Thu, 14 Jun 2018 03:04:35 +0000
From:   Robin Gong <yibin.gong@....com>
To:     "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>
CC:     "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH v3 0/6] add virt-dma support for imx-sdma

Hi Lucas,
	I have identified the root cause besides the lockdep issue.
Will contain the UART patch into my next v4 patchset.

Hi Sascha,
	Will address your comments in v4 too. Thank you both input.

On 三, 2018-06-13 at 18:07 +0200, Lucas Stach wrote:
> Hi Robin,
> 
> Am Dienstag, den 12.06.2018, 08:58 +0000 schrieb Robin Gong:
> > 
> > Hi Lucas,
> > 	Is the below DEAD LOCK issue same as your side? If yes, then
> > I'm afraid that we have to make another patch for uart to split dma
> > functions in uart driver out of the code area which protected by
> > port.lock. The warning make sense since allocate sdma bd memory
> > dynamically in virt-dma instead of static allocated as before. I'll
> > make another uart patch into my next version patchset.
> Yes, I see the same lockdep splat on my system. Though I'm not sure
> if
> this is really the root cause of the issue I see.
> 
> I'm getting timeouts for a serdev attached device and I don't think
> this system ever enters memory reclaim, so the issue reported by
> lockdep seems to be a mostly theoretical on this system. But lets see
> how far I get when you fixed this issue, maybe the real bug is hiding
> behind this one.
> 
> Regards,
> Lucas