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

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Date:   Wed, 13 Jun 2018 18:07:52 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Robin Gong <yibin.gong@....com>,
        "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 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