Re: AM335x BeagleBone SPI Issues

Jack Mitchell <ml@xxxxxxxxxxxxxxxxxxx> · Tue, 11 Dec 2012 16:24:52 +0000

On 11/12/12 15:22, Ben Gamari wrote:
Jack Mitchell <ml@xxxxxxxxxxxxxxxxxxx> writes:

Shubhro, Felipe,

Thank you, the reordering dma patch fixed the dma issue I was having!
However, the bad news, I now get the same results for the dma and
non-dma spidev test. While the scope shows the SPI clk and data is fine,
the reading from the program still shows 0x00 for all words.

Just to make sure this has been thought of: I've seen this sort of
behavior in the past when the CLK pin wasn't configured as an input.

Cheers,

- Ben

Ok, Ben, well spotted indeed! I changed the dtsi to use INPUT_PULLUP 
instead of OUTPUT_PULLUP and wallah!

  am3358_pinmux: pinmux@44e10800 {
    spi0_pins: pinmux_spi0_pins {
      pinctrl-single,pins = <
        0x150 *0x30*      /* spi0_sclk.gpio0_2, INPUT_PULLUP | MODE0 
*/<------------ changed to INPUT
        0x154 0x30      /* spi0_d0.gpio0_3, INPUT_PULLUP | MODE0 */
        0x158 0x10      /* spi0_d1.i2c1_sda, OUTPUT_PULLUP | MODE0 */
        0x15c 0x10      /* spi0_cs0.i2c1_scl, OUTPUT_PULLUP | MODE0 */
      >;
    };
    spi1_pins: pinmux_spi1_pins {
      pinctrl-single,pins = <
        0x190 *0x33*  /* mcasp0_aclkx.spi1_sclk, INPUT_PULLUP | MODE3 
*/ <------------ changed to INPUT
        0x194 0x33  /* mcasp0_fsx.spi1_d0, INPUT_PULLUP | MODE3 */
        0x198 0x13  /* mcasp0_axr0.spi1_d1, OUTPUT_PULLUP | MODE3 */
        0x19c 0x13  /* mcasp0_ahclkr.spi1_cs0, OUTPUT_PULLUP | MODE3 */
      >;
    };

root@beaglebone:~# ./spidev
spi mode: 0
bits per word: 16
max speed: 24000000 Hz (24000 KHz)

FF FF FF FF FF FF
40 00 00 00 00 95
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
DE AD BE EF BA AD
F0 0D
root@beaglebone:~# ./spidev_dma
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)

FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00
FF 00 FF 00 FF 00

We are in business!

Almost.

I then tried spi1 and received:

root@beaglebone:~# ./spidev -D /dev/spidev2.0
spi mode: 0
bits per word: 16
max speed: 24000000 Hz (24000 KHz)

FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF
root@beaglebone:~# ./spidev_dma -D /dev/spidev2.0
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)

FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
FF FF FF FF FF FF
root@beaglebone:~#

--

  Jack Mitchell (jack@xxxxxxxxxxx)
  Embedded Systems Engineer
  http://www.embed.me.uk

--

--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html