On Thu, Nov 5, 2015 at 3:47 PM, Robert Nelson <[email protected]> wrote: > The journey into spi & dma.. > > So for awhile now, we've had a bug for spi users, where the system > would hardlock at the "160" byte threashold: > > debian@beaglebone:~$ sudo dd if=/dev/zero of=/dev/spidev1.0 bs=159 count=1 > 1+0 records in > 1+0 records out > 159 bytes (159 B) copied, 0.000508833 s, 312 kB/s > debian@beaglebone:/sys$ dd if=/dev/zero of=/dev/spidev1.0 bs=160 count=1 > ^C > > (hangs..) > > "160" happens to be a the magic number where DMA takes over from PIO mode... > > Well as of yesterday: > > debian@beaglebone:~$ sudo dd if=/dev/zero of=/dev/spidev1.0 bs=320 count=1 > 1+0 records in > 1+0 records out > 320 bytes (320 B) copied, 0.00266366 s, 120 kB/s > > So here's the deal, it looks to be a spi/overlay bug, as we don't seem > to get the correct dma tx/rx channels.. > > What interesting, when the "spi" node is enabled in the main dtb: > > https://github.com/RobertCNelson/dtb-rebuilder/blob/4.1-ti/src/arm/am335x-boneblack-spi0.dts#L120-L137 > > it works fine in dma mode... > > So with "4.1.12-ti-r27" spi-dma is now disabled.. > > *btw: > > Late last night i wrote a better fix (will be r28) > > where you can disable "spi-dma" via the dt option: > > ti,pio-mode; > > https://github.com/beagleboard/bb.org-overlays/commit/48d33d4d22f284103db83626b343724cf18c578d > > Regards, > It is very long time ago, but now I am running into performance issues with SPI. I see the DMA is still disabled in current bb.org-overlays. So is the bug for blocks > 160 still there (what about kernel 4.4.x?)
Thanks in advance Andreas -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CALbNGRSqXpYEd1p2bMKngZKZz-mGZOshv%3D3Os1WcdscvAh5dtg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
