i.MX Processors中的主题 Re: SPI read/write with changing modes fail

SPI read/write with changing modes fail

abhinandanbr — Mon, 16 Sep 2019 12:13:47 GMT

Hi all,

I am testing spi read and write in imx6 as master. The method of my testing includes testing read/write for all modes.

So, first I test read/write separately for SPI mode 0... then do the same read/write test for mode 1... then for mode 2 and finally mode 3.

But this sequence of changing modes and repeating the read/write test is failing.

A single test application is used to test the above sequence.

If we change the sequence of testing to SPI mode 1, mode 0 mode 3 and then mode 2 in the end, it is found to be working fine and also this sequence is repeatable.

In all cases, frame size is 32bits and data length is 12 bytes.

Below is the spi configuration used in imx6 dts

&ecspi2 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_ecspi2>;
fsl,spi-num-chipselects = <2>;
cs-gpios = <&gpio2 26 0>, <&gpio2 27 0>;
dmas = <&sdma 5 7 1>, <&sdma 6 7 2>;
dma-names = "rx", "tx";
status = "okay";

spi@0 {
compatible = "spidev";
spi-max-frequency = <50000000>;
reg = <0>;
};

spi@1 {
compatible = "spidev";
spi-max-frequency = <50000000>;
reg = <1>;
};

}

Please let me know if this behavior is expected in this testing.

If not, please point me to the recommended fix I can try out, so that all sequences works.

Regards,

Abhinandan

Re: SPI read/write with changing modes fail

igorpadykov — Tue, 17 Sep 2019 09:52:55 GMT

Hi Abhinandan

to avoid such issues one can try to follow sect.21.5 Initialization before each mode

i.MX 6Dual/6Quad Applications Processor Reference Manual

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: SPI read/write with changing modes fail

abhinandanbr — Wed, 18 Sep 2019 10:33:00 GMT

Hi Igor,

Thanks for the reply.

The section indicates code changes from the driver point of view.

But from the application perspective, is it possible to follow the steps mentioned in the sect. 21.5?

I am using the SPI driver available as part of Yocto BSP18.1.0.

Regards,

Abhinandan

Re: SPI read/write with changing modes fail

igorpadykov — Wed, 18 Sep 2019 13:28:35 GMT

Hi Abhinandan

section indicates code changes from the hardware point of view.

So violating it may cause ecspi module malfunction.

Best regards
igor