> On Dec 16, 2015, at 2:38 PM, Robert Nelson <[email protected]> wrote: > >>> >>> SPI works great on v4.1.x now, just pay attention this this little >>> spi-dma-disable hack: >>> >>> https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-SPIDEV0-00A0.dts#L54 >>> >>> "ti,pio-mode;" >>> >>> Otherwise, the spidev interface will lock up on the 160'th bit... >>> >>> (3.8 never used dma on spi, so this isn't a regression in speed..) >> I believe the problem is in spidev which probably doesn't allocate >> DMA-coherent memory for the buffer. If you use McSPI and allocate >> DMA-coherent memory for the buffer it works just fine for > 160 bytes. > > But it works when the "spi & spidev" node is in the initial *.dtb, but > not as an overlay. It seems like when loaded as an overlay we aren't > getting the correct dma channel/memory/etc.. That doesn’t make sense to me. I know a few months ago I was working on a SPI driver and I had the same issue when my buffer exceeded 160 bytes. When I used a DMA-coherent buffer, my driver worked fine. I was using an overlay to load my driver during testing. My driver did not use SPIDEV.
Regards, John > > Regards, > > > -- > Robert Nelson > https://rcn-ee.com/ > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
