linux-kernel - Re: [PATCH 2/2] ARM: dts: imx7: add DMA properties for ECSPI

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Date:   Tue, 12 Feb 2019 22:57:23 -0200
From:   Fabio Estevam <festevam@...il.com>
To:     Trent Piepho <tpiepho@...inj.com>
Cc:     "linux-imx@....com" <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "stefan@...er.ch" <stefan@...er.ch>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "fabio.estevam@....com" <fabio.estevam@....com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
Subject: Re: [PATCH 2/2] ARM: dts: imx7: add DMA properties for ECSPI

On Tue, Feb 12, 2019 at 10:07 PM Trent Piepho <tpiepho@...inj.com> wrote:

> Tried SDMA firmware 4.2.  Still broken.  No apparent change.
>
> Get 4 cycle pause after each byte.
>
> And crash while/after using DMA.  Clearly some sort of memory
> corruption going on.  Fortunately, it's very reliable that using DMA
> almost immediately causes a problem and this is easy to reproduce.  I
> think that indicates it's either clobbers a lot of RAM, or consistently
> manages to hit a very important location for kernel memory allocators.
>
> I've got an idea of where that might be happening that I'm looking
> into.

Ok, thanks for investigating this issue.

>
> I think it's reasonable to add the dma attributes, but put a check in
> the spi-imx driver to disable DMA on imx7d at least.

Something like this?
http://dark-code.bulix.org/urfoh8-580174