Some questions regarding device tree and ecspi

[heinrichgeiger]

Hello colleagues,

I am developing a driver for TI SRC4193 (asynchronous sample-rate converter) and have some questions regarding the device tree.

The SRC4193 is connected to ECSPI2, here the configuration:

&ecspi2 {
fsl,spi-num-chipselects = <2>;
cs-gpios = <&gpio5 12 GPIO_ACTIVE_LOW>
, <&gpio5 9 GPIO_ACTIVE_LOW>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_ecspi2>;
status = "okay";

src4193@0 {
compatible="ti,src4193";
spi-max-frequency = <10000000>;
};
};

Pinmux looks like this:

&iomuxc {

...
pinctrl_ecspi2: ecspi2grp {
fsl,pins = <
MX6QDL_PAD_DISP0_DAT16__ECSPI2_MOSI 0x100b1
MX6QDL_PAD_DISP0_DAT17__ECSPI2_MISO 0x100b1
MX6QDL_PAD_DISP0_DAT19__ECSPI2_SCLK 0x100b1
MX6QDL_PAD_DISP0_DAT18__ECSPI2_SS0 0x000b1 /* CS0 */
MX6QDL_PAD_DISP0_DAT15__ECSPI2_SS1 0x000b1 /* CS1 */
>;
};
....
};

ECSPI2 has two CS lines.

My questions:

1. How can I explicitly assign a CS line (in this case CS1) to the SRC4193?

2. When do the settings in PINMUX become active? When booting? When loading the driver for SRC4192?

My hardware and sorftware:

Linux: Kernel 4.9.88 with boundary devices RootFS

Soc: i.MX6Dual on Embest MarsBoard

Many thanks and regards,

Heinrich

[darko1]

I am also using i.MX6Dual on Embest MarsBoard

With the following setup:

&ecspi2 {     
fsl,spi-num-chipselects = <1>;     
cs-gpios = <&gpio2 26 GPIO_ACTIVE_LOW>;     
pinctrl-names = "default";     
pinctrl-0 = <&pinctrl_ecspi2>;     
status = "okay";      

spidev@0x00 {         
compatible = "spidev";         
spi-max-frequency = <20000000>;         
reg = <0>;     
}; 

};

Following this procedure:

https://github.com/FrankBau/meta-marsboard-bsp/wiki/Using-SPI

I get no output signals on pins 15,17,19,21 on J11 connector. Just 50 Hz noise signal, all the time

Any idea why there is no output on pins ?

Loop test on SPI is working and device /dev/spidev1.0 is active.

[darko1]

Just to help someone else with same issue. Correct pins for MarSBoard and ecspi2 are given in the picture.

It now works correctly with 

 MX6QDL_PAD_EIM_RW__GPIO2_IO26           0x1b0b1 /* SS0 */   

[igorpadykov]

Hi Heinrich

boundary devices RootFS is not supported by nxp, it is supported by boundary devices

support. For nxp dts ecspi example with "cs-gpios" one can look at

imx6qdl-sabresd.dtsi\dts\boot\arm\arch - linux-imx - i.MX Linux kernel 

patch for support native ecspi cs :

[v4,1/3] spi: imx: GPIO chip select DT property should not be required - Patchwork 

Best regards
igor
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