On Tue, 2019-02-12 at 17:37 -0200, Fabio Estevam wrote: > On Mon, Feb 11, 2019 at 8:22 PM Trent Piepho <tpie...@impinj.com> > wrote: > > > > Just trying to understand if the SDMA firmware plays a role on > > > this > > > behavior or not. > > > > The ROM firmware only. > > Does the problem also happen if the external SDMA firmware is used? > Just trying to narrow it down.
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. 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.
