Nice work, Robert.

Are the recent PRU-related changes in this update?

> On Nov 5, 2015, at 06:47 , 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,
> 
> -- 
> Robert Nelson
> https://rcn-ee.com/
> 
> -- 
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-- 
Rick Mann
[email protected]


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