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SubjectRe: [PATCH 2/2] ARM: dts: imx7: add DMA properties for ECSPI
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On Mon, 2019-02-11 at 19:34 -0200, Fabio Estevam wrote:
> Hi Trent,
>
> On Mon, Feb 11, 2019 at 6:44 PM Trent Piepho <tpiepho@impinj.com> wrote:
>
> > I've had more time to test.
> >
> > Without DMA, I can reload my FPGA hundreds of times and get days of
> > uptime using linux-next.
> >
> > With DMA, loading is unreliable. The higher the SPI speed, the less
> > reliable it is. Unfortunately, it's hard to duplicate the problem with
> > a small amount of data, and with a large amount of data I can't examine
> > it in depth enough to determine if the problem is related to SPI bus
> > timing or IMX sDMA sending the wrong bytes to the spi controller.
> >
> > Using DMA with SPI causes kernel panics. Not always immediately, but
> > after using DMA it's a smaller of minutes before something crashes.
> > The backtraces are all over the place and don't usually point back into
> > SPI. It does seem like they usually hit something has allocated or is
> > allocating DMA memory.
>
> Did you test with an external SDMA firmware or with the ROM SDMA firmware?
>
> Just trying to understand if the SDMA firmware plays a role on this
> behavior or not.

The ROM firmware only.
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