[meta-freescale] [PATCH] spi-imx -> make DMA optional through DT

[Fabio Estevam]

Hi Hans,

On Wed, Mar 30, 2016 at 3:14 AM, Hans Christian Lønstad
<hcl at datarespons.no> wrote:

> The issue surfaced after DT introduced the DMA functionality (imx6qdl.dtsi).
> This applies to mainline kernels (checked 4.1 and up) as well.
> It is my understanding that SPI DMA is performed using scatter/gather which
> should be able to handle vmalloc’ed memory, so the question remains wether
> the root cause lies within the DMA code or is some kind of coherence issue
> within the UBIFS code.
>
> Anyway, the benefit from DMA might be questionable for this use case (we are
> using SPI NOR for VPD product data), so we are happy just disabling it.
>
> The issue must be considered grave as it bricks systemd trying to mount an
> UBIFS during startup.

Thanks for reporting the issue.

It would be better if we could fix the DMA issue instead of disabling it.

If you are able to reproduce this with a mainline kernel, it would be
nice to report this bug into the linux-spi mailing list, so that other
people could potentially help with it.