topic Re: i.MX25 SPI problem in i.MX Processors

i.MX25 SPI problem

csotoalonso — Sun, 30 Nov 2014 21:46:52 GMT

Hi,

I'm trying to enable SPI in the TX25 module from KaRo. I'm using kernel 3.17.2, and in order to enable SPI i've modified imx25-karo-tx25.dts. The changes are two: first of all, enable SPI

/* SPI support */

&spi1 {

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_cspi>;

fsl,spi-num-chipselects = <2>;

status = "okay";

cs-gpios = <

&gpio1 16 0

&gpio1 17 0

spidev0: spi@0 {

compatible = "spidev";

reg = <0>;

spi-max-frequency = <24000000>;

};

spidev1: spi@1 {

compatible = "spidev";

reg = <1>;

spi-max-frequency = <24000000>;

};

And

pinctrl_cspi: cspigrp {
	fsl,pins = <
		MX25_PAD_CSPI1_RDY__CSPI1_RDY	0x80000000
		MX25_PAD_CSPI1_SS0__CSPI1_SS0	0x80000000
		MX25_PAD_CSPI1_SCLK__CSPI1_SCLK	0x80000000
		MX25_PAD_CSPI1_MISO__CSPI1_MISO	0x80000000
		MX25_PAD_CSPI1_MOSI__CSPI1_MOSI	0x80000000
		MX25_PAD_CSPI1_SS1__CSPI1_SS1	0x80000000
	>;
};

to iomuxc.

I've created a rootfs with buildroot, and added spidev_test to it. When I try this command, the process hangs and I'm unable to end it, even with a kill -9.

Further debugging using strace has shown that the process hangs when tries to execute this ioctl:

ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);

but that's as far as I can get.

Any clues? Thanks in advance

Re: i.MX25 SPI problem

fabio_estevam — Mon, 01 Dec 2014 01:11:08 GMT

Carlos,

Please configure the chip select IOMUX as GPIO functionality instead of native SPI chip select functionality.

Re: i.MX25 SPI problem

csotoalonso — Mon, 01 Dec 2014 15:16:50 GMT

Fabio,

do you mean, instead of MX25_PAD_CSPI1_MISO__CSPI1_MISO, using MX25_PAD_CSPI1_MISO__GPIO_1_15?

I've tried that, and no luck. spidev_test keeps hanging inmediately after the call to ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);

Thanks for your answer.

Re: i.MX25 SPI problem

fabio_estevam — Mon, 01 Dec 2014 15:19:38 GMT

No, not MISO as GPIO. I meant MX25_PAD_CSPI1_SS0__ and MX25_PAD_CSPI1_SS1__ as GPIOs.

Re: i.MX25 SPI problem

csotoalonso — Mon, 01 Dec 2014 15:31:44 GMT

OK, sorry.

My new IOMUX looks like this:

pinctrl_cspi: cspigrp {

fsl,pins = <

MX25_PAD_CSPI1_RDY__CSPI1_RDY 0x80000000

MX25_PAD_CSPI1_SS0__GPIO_1_16 0x80000000

MX25_PAD_CSPI1_SCLK__CSPI1_SCLK 0x80000000

MX25_PAD_CSPI1_MISO__CSPI1_MISO 0x80000000

MX25_PAD_CSPI1_MOSI__CSPI1_MOSI 0x80000000

MX25_PAD_CSPI1_SS1__GPIO_1_17 0x80000000

};

But it doesn't work either. It hangs in the same exact place. Is there anything special I should put in the CONFIG pad settings?

Re: i.MX25 SPI problem

jimmychan — Thu, 04 Dec 2014 03:31:17 GMT

Could you show your test program?

Re: i.MX25 SPI problem

csotoalonso — Thu, 04 Dec 2014 13:35:33 GMT

I'm using the standard spidev_test from the kernel:

https://www.kernel.org/doc/Documentation/spi/spidev_test.c

Re: i.MX25 SPI problem

fabio_estevam — Thu, 04 Dec 2014 14:18:05 GMT

Hi Carlos,

The '0x80000000' means that the kernel will not configure the PAD settings and then it just uses whatever value that comes from the bootloader.

So it would be better to check the configuration you are getting and pass it in the dts.

Re: i.MX25 SPI problem

csotoalonso — Thu, 04 Dec 2014 15:14:01 GMT

Hi Fabio,

I think I tried configuring the PAD setting for GPIO1_16 and GPIO1_17 in the DTS following the document fsl,imx25-pinctrl.txt, I don't have in front of me the values I used, but I can check it later. That didn't work either. Should I also configure the PAD settings for the SPI pins also (MISO, MOSI & SCLK)? If that's the case, would you mind helping me with this configuration?

Thanks

Re: i.MX25 SPI problem

fabio_estevam — Thu, 04 Dec 2014 15:33:55 GMT

Hi Carlos,

For GPIO pins you can let them in thde default reset values.

For the pins with SPI funcionality you need to adjust them.

I recommend you looking at the SPI_PAD_CTL1 and SPI_PAD_CTL2 configurations defined at:

linux-2.6-imx.git - Freescale i.MX Linux Tree

This is from kernel 2.6.31, but they can be easily adapted in your dts.

Re: i.MX25 SPI problem

csotoalonso — Fri, 05 Dec 2014 17:48:37 GMT

OK, Fabio, thanks for pointing me in the right direction.

I've changed the PAD settings for the IOMUX based on SPI_PAD_CTL1, and now my DTS looks like this:

pinctrl_cspi: cspigrp {

fsl,pins = <

MX25_PAD_CSPI1_RDY__CSPI1_RDY 0x1A0

MX25_PAD_CSPI1_SS0__GPIO_1_16 0x80000000

MX25_PAD_CSPI1_SCLK__CSPI1_SCLK 0x1A0

MX25_PAD_CSPI1_MISO__CSPI1_MISO 0x1A0

MX25_PAD_CSPI1_MOSI__CSPI1_MOSI 0x1A0

MX25_PAD_CSPI1_SS1__GPIO_1_17 0x80000000

};

But the problem is the same: when I launch spidev_test, it hangs in ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);

I've also tried in another module to check for hardware problems, but with the same result.

Any hint would be very much appreciated at this point, I'm getting a bit desperate here :smileysad:

Re: i.MX25 SPI problem

fabio_estevam — Fri, 05 Dec 2014 18:03:03 GMT

What spi device are you connecting to the mx25?

As you are getting a hang? I suspect that the SPI clocks are not being turned on, so I would recommend you probing the spi clocks with a scope.

Re: i.MX25 SPI problem

fabio_estevam — Fri, 05 Dec 2014 18:07:18 GMT

Hi Carlos,

I think I found the bug, in imx25.dtsi, please change the clocks line as below:

		spi1: cspi@43fa4000 {
			#address-cells = <1>;
			#size-cells = <0>;
			compatible = "fsl,imx25-cspi", "fsl,imx35-cspi";
			reg = <0x43fa4000 0x4000>;
			clocks = <&clks 78>, <&clks 78>;
			clock-names = "ipg", "per";
			interrupts = <14>;
			status = "disabled";
		};

Re: i.MX25 SPI problem

csotoalonso — Sat, 06 Dec 2014 18:33:49 GMT

Wow!

I didn't see your answer yesterday, and today I was checking your last answer regarding the clocks, so I checked imx25-clock.txt against the DTSI, and yeah! The clock assignment was wrong... I changed che clocks property into my dts and it works perfectly now.

So when I was coming here to post the answer I see you have already posted it. Should have looked before:smileyshocked:

Anyway, it is working now, and in the process I've gained a greater insight into the Device Tree business so thank you very much, Fabio! :smileyhappy:

Re: i.MX25 SPI problem

fabio_estevam — Sat, 06 Dec 2014 19:17:04 GMT

Hi Carlos,

Glad to know it is working now :-)

Yesterday I sent the fix to the linux-arm-kernel mailing list:

[PATCH] ARM: dts: imx25: Fix the SPI1 clocks — ARM, OMAP, Xscale Linux Kernel