The kmm_malloc() also has the same effect of making it work. I think what's going on is that the transfer is passing a SDMA Buffer Boundary— they are 4kb (configurable, but that's the default). SDMA pauses when passing one, and needs to be reenabled by software. I can see the SDMMC_INT_DINT being fired when I dump the SDMMC registers, but that interrupt is not enabled for some reason... I'm trying to track it down now.
-adam On Tue, Jul 7, 2020 at 9:09 PM Adam Feuer <a...@starcat.io> wrote: > Greg, > > Thanks. I'll change the call to kmm_malloc() or kmm_memalign() and see if > that works too. > > cheers > adam > > On Tue, Jul 7, 2020 at 9:03 PM spudaneco <spudan...@gmail.com> wrote: > >> I don't know anything about the DMA, but you should not call calloc() >> from within the OS. That does not work in all configurations.Instead >> include nuttx/kmalloc,h and call kmm_malloc(). If you want aligned memory, >> call kmm_memalgn().Sent from Samsung tablet. >> -------- Original message --------From: Adam Feuer <a...@adamfeuer.com> >> Date: 7/7/20 9:40 PM (GMT-06:00) To: dev@nuttx.apache.org Subject: >> driver question about memory and calloc Hi,I am getting the SAMA5D27 SDMMC >> SD Card driver pull request ready. There'sone small issue I'm working on, >> though. There's a place in the driverinitialization where I calloc() some >> memory– 466 bytes. DMA data transferswhile reading from files times out if >> I don't have the calloc() in there.With the memory allocated, everything >> works fine. Nothing writes to thisblock of memory– I memset it and examined >> it before, during, and aftertransfers using GDB. It's just an unused block >> of memory.I'm trying to find out if other amounts of memory work– smaller >> than about100 bytes doesn't work, and I know it works reliably at 466 >> bytes. I'lltrack the exact number down tomorrow.But my question is, why >> does this work? The driver datasheets< >> http://ww1.microchip.com/downloads/en/devicedoc/ds60001476b.pdf>don'tmention >> that the chip needs aligned memory for its buffers, and the Atmeland U-Boot >> drivers don't use aligned memory. And since nothing isoverwriting the >> memory, what is the calloc() doing to prevent the SDMMC DMAengine from >> completing the transfer?If anyone has seen behavior like this, I'd love to >> know it. I'd like totake this otherwise useless code out, or at least know >> why I need it.Link to the specific line of code in sam_sdmmc.c< >> https://github.com/starcat-io/incubator-nuttx/blob/feature/sama5d27-sdmmc-support/arch/arm/src/sama5/sam_sdmmc.c#L3737>cheersadam-- >> Adam Feuer <a...@adamfeuer.com> > > > > -- > Adam Feuer <a...@starcat.io> > -- Adam Feuer <a...@starcat.io>
