ECSPI2 on i.MX 8M Nano EVK - CS not working as GPIO due to CONFIG_SPI_GPIO?

[sibo]

Hi everyone,

I have a problem using the ECSPI2 on the i.MX 8M Nano Evaluation Kit and have already the idea, that the CONFIG_SPIO_GPIO has to be set in kernel configuration, but I can't find a way to do that.

This is my first question here, I hope that I give enough explanation what I did and what I want to archieve. If not, let me know and I will fix it :smileyhappy:

I am using yocto with following build configuration:

Build Configuration:
BB_VERSION = "1.44.0"
BUILD_SYS = "x86_64-linux"
NATIVELSBSTRING = "ubuntu-18.04"
TARGET_SYS = "aarch64-poky-linux"
MACHINE = "imx8mnevk"
DISTRO = "fsl-imx-xwayland"
DISTRO_VERSION = "5.4-zeus"
TUNE_FEATURES = "aarch64"
TARGET_FPU = ""

Following the example ECSPI2 on i.MX8M Mini EVK

I created my own layer with "recipes-kernel/linux" in it and made a patch for the kernel with

bitbake -c devshell linux-imx

changing the ECSPI2 in the device-tree arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts

according to the example and arch/arm64/boot/dts/freescale/imx8mn-pinfunc.h

But I changed the PAD Configure value for ECSPI2_SS0 to 0x82, disabeling the Pulldown-resistor due to

i.MX 8M Nano Applications Processor Reference Manual - 8.2.5.233 Pad Control Register (IOMUXC_SW_PAD_CTL_PAD_ECSPI2_SS0)

and

git format-patch -n HEAD^

putting the created patch in recipes-kernel/linux/files and calling it in recipes-kernel/linux/linux-imx_5.4.bbappend file:

FILESEXTRAPATHS_prepend := "${THISDIR}/files:"

SRC_URI += "file://0001-adding-ecspi-and-spidev.patch"

On the board, the Configs for spi are already set as default in /proc/config.gz:

CONFIG_SPI=y
CONFIG_SPI_MASTER=y

...

CONFIG_SPI_BITBANG=y

etc.

When I run

root@imx8mnevk:/unit_tests/ECSPI# ./mxc_spi_test1.out -D 0 -s 12000 -b 8 1337

I see MISO, MOSI, SCK and CS working as expected.

Now, I wanted to change the CS line to a gpio-configuration.

I repeated the former steps, creating an imx8mn-ddr4-evk.dts-patch looking like that:

@@ -282,6 +282,27 @@
                >;
        };

+       pinctrl_ecspi2: ecspi2grp {
+               fsl,pins = <
+                       MX8MN_IOMUXC_ECSPI2_SCLK_ECSPI2_SCLK            0x1916
+                       MX8MN_IOMUXC_ECSPI2_MOSI_ECSPI2_MOSI            0x116
+                       MX8MN_IOMUXC_ECSPI2_MISO_ECSPI2_MISO            0x116
+               >;
+       };
+
+       pinctrl_ecspi2_cs: ecspi2cs {
+                fsl,pins = <
+                        MX8MN_IOMUXC_ECSPI2_SS0_GPIO5_IO13              0x82
+                >;
+        };
+
+       //Pin Configurations
+       //Pin Ctrl from imx8mn-pinfunc.h
+       //Pad Ctrl from i.MX 8M Nano Applications Processor Reference Manual
+       //8.2.5.247 Pad Control Register (IOMUX_SW_PAD_CTL_PAD_UART3_TXD)
+       // HYS = 1
+       // DSE = 0x01X
+

        pinctrl_usdhc1_gpio: usdhc1grpgpio {
                fsl,pins = <
                        MX8MN_IOMUXC_SD1_RESET_B_GPIO2_IO10     0x41
@@ -754,6 +775,21 @@
        status = "okay";
 };

+&ecspi2 {
+        fsl,spi-num-chipselects = <1>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_ecspi2 &pinctrl_ecspi2_cs>;
+        cs-gpios = <&gpio5 13 GPIO_ACTIVE_LOW>;
+        status = "okay";
+
+       it8951spi: it8951spi@0 {
+             compatible = "ite,it8951_spi_protocol";
+             reg = <0>;

+ spi-max-frequency = <12000000>;
+ spi-epaper-frequency = <24000000>;
+ };
+};
+
&usbotg1 {
picophy,pre-emp-curr-control = <3>;
picophy,dc-vol-level-adjust = <7>;
--
2.17.1

I made an out-of-tree-kernel module doing nothing but writing 0x04 0x04 to spi line, wich is automatically loaded at boot by defining

CORE_IMAGE_EXTRA_INSTALL = "spi-it8951"
KERNEL_MODULE_AUTOLOAD += "spi-it8951"

in <yocto_dir>/<build_dir>/conf/local.conf

I can see that the module is loaded by lsmod:

root@imx8mnevk:~# lsmod
Module                  Size  Used by
crct10dif_ce           16384  1
brcmfmac              303104  0
brcmutil               20480  1 brcmfmac
spi_it8951             16384  0
galcore               512000  0

and I can see the data on the MISO line, as well as a Clock generated for it.

But what I am missing is the CS pin toggeling.

When I analyze the /proc/config.gz, theres a value CONFIG_SPI_GPIO which is not set.

Could that be the missing configuration? And If yes, how can I enable it?

I tried to make a spigpio.cfg in recipes-kernel/linux/files and adding it to linux-imx_5.4.bbappend, which includes:

CONFIG_SPI_GPIO=y

I can see the file popping up in

<yocto_dir>/<build_dir>/tmp/work/imx8mnevk-poky-linux/linux-imx/5.4-r0/spigpio.cfg

but nothing changed.

On the board, in /proc/config.gz CONFIG_SPI_GPIO is still not set.

The same happens when I patch the  /arch/arm64/configs/imx_v8_defconfig file.

I can see that the change took place by having a look in

<yocto_dir>/<build_dir>/tmp/work-shared/imx8mnevk/kernel-source/arch/arm64/configs/imx_v8_defconfig

but the config.gz on the board still says "CONFIG_SPI_GPIO is not set" -.-

Is there a way to set this config? Or am I hunting the white rabbit anyway and the config does not change my CS Problem?

I am running out of ideas. Any help would be highly appreciated!

I know, this is a lot of infos around the problem, but I wanted to make it as clear as possible to follow.

Thanks,

Silke

[sibo · Accepted solution]

After spending time in the spi-imx driver, I found the solution

https://community.nxp.com/message/1326698?commentID=1326698#comment-1326698

Best Regards,

Silke

[sibo]

Things are getting quite strange.

For testing purpose, I put two spi child nodes into the ecspi2 node, using different Chip Select lines, one as a gpio, the other one as native CS.

---
.../boot/dts/freescale/imx8mn-ddr4-evk.dts | 73 ++++++++++++++++++-
1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts b/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
index 039ece96b9b2..2e77926e7663 100644
--- a/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
+++ b/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
@@ -158,6 +158,36 @@
>;
};

+ pinctrl_ecspi2: ecspi2grp {
+ fsl,pins = <
+ MX8MN_IOMUXC_ECSPI2_SCLK_ECSPI2_SCLK 0x156
+ MX8MN_IOMUXC_ECSPI2_MOSI_ECSPI2_MOSI 0x156
+ MX8MN_IOMUXC_ECSPI2_MISO_ECSPI2_MISO 0x156
+ MX8MN_IOMUXC_ECSPI2_SS0_ECSPI2_SS0 0x156
+ MX8MN_IOMUXC_SAI5_RXD2_GPIO3_IO23 0x156
+ >;
+ };
+
+ pinctrl_it8951_reset_pin: it8951_reset_grp {
+ fsl,pins = <
+ MX8MN_IOMUXC_SAI5_RXD0_GPIO3_IO21 0x156
+ >;
+ };
+
+ pinctrl_it8951_hrdy_pin: it8951_hrdy_grp {
+ fsl,pins = <
+ MX8MN_IOMUXC_SAI5_RXC_GPIO3_IO20 0x156
+ >;
+ };
+
+ //Pin Configurations
+ //Pin Ctrl from imx8mn-pinfunc.h
+ //Pad Ctrl from i.MX 8M Nano Applications Processor Reference Manual
+ //8.2.5.247 Pad Control Register (IOMUX_SW_PAD_CTL_PAD_UART3_TXD)
+ // HYS = 1
+ // DSE = 0x01X
+
+
pinctrl_pmic: pmicirq {
fsl,pins = <
MX8MN_IOMUXC_GPIO1_IO03_GPIO1_IO3 0x41
@@ -710,6 +740,45 @@
};
};

+&ecspi2 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ fsl,spi-num-chipselects = <2>; //obsolete, this or num-cs?
+ num-cs = <2>; //not sure what imx-ler will use
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_ecspi2>;
+ cs-gpios = <&gpio3 23 GPIO_ACTIVE_LOW>, <0>;
+ gpios = <&gpio3 23 GPIO_ACTIVE_LOW>, <0>; //not sure what imx-ler will use
+ status = "okay";
+
+ it8951spi: it8951spi@0 {
+ compatible = "ite,it8951_spi_protocol";
+ reg = <0>; //first cs, so gpio
+ spi-max-frequency = <12000000>;
+ spi-epaper-frequency = <24000000>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_it8951_reset_pin>, <&pinctrl_it8951_hrdy_pin>;
+ hrdy_gpio = <&gpio3 20 GPIO_ACTIVE_LOW>;
+ rst_gpio = <&gpio3 21 GPIO_ACTIVE_HIGH>;
+
+ preamble_read = /bits/ 16 <0x1000>;
+ preamble_write = /bits/ 16 <0x0000>;
+ preamble_command = /bits/ 16 <0x6000>;
+
+ vcom = /bits/ 16 <2040>; //e.g. -1.77 V = 1770
+ display_mode = /bits/ 8 <1>; //monochrome
+ display_mode_pictures = /bits/ 8 <2>; //pre gray
+ status = "okay";
+ };
+
+ spidev: spidev@0{
+ compatible = "spidev";
+ spi-max-frequency = <10000000>;
+ reg = <1>; //second cs, native
+ };
+};
+
+
&lcdif {
status = "okay";
};
@@ -736,7 +805,7 @@
assigned-clock-parents = <&clk IMX8MN_SYS_PLL1_80M>;
fsl,uart-has-rtscts;
resets = <&modem_reset>;

- status = "okay";
+ status = "disabled";
};

&uart2 { /* console */
@@ -834,7 +903,7 @@
assigned-clocks = <&clk IMX8MN_CLK_PDM>;
assigned-clock-parents = <&clk IMX8MN_AUDIO_PLL1_OUT>;
assigned-clock-rates = <196608000>;
- status = "okay";
+ status = "disabled";
};

&sai3 {
--
2.17.1

Altough i put reg = <0> in spi child node for it8951spi and defining this as the gpio in ecspi2,

the natice CS line is toggled -.-

The other GPIOs, named RST and HRDY work as expected. As you already see in my device-tree-patch, I tried different names for cs-gpios and num-cs.

When I mux the native CS to a GPIO instead of another GPIO on the pin header, I just see nothing on this line.

I am confused, because everywhere in the internet, people are suggested to use GPIO instead of native CS and it seems to work for them, so I must do something stupid and wrong in my patch...

Using native CS is no option, because it toggles every 8 bit and my controller does not understand that.

Any suggestions how to move on?

Thanks,

Silke

[jimmychan]

This may help you.

https://community.nxp.com/message/1021332 

[sibo]

Hi jimmychan,

thanks for the response and the link.

I tried it out, but it did not work in my case.

I also tried to debug in the spi-imx.c driver, making a lot of printks in it.

One, where I moved the gpio-requesting block of code in spi_imx_probe

to a spot before bitbang_start and one after.

See the one with the switch below:

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 91e32291c44e..4a9c27415009 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -1553,7 +1553,7 @@ static int spi_imx_transfer(struct spi_device *spi,

static int spi_imx_setup(struct spi_device *spi)
{
- dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n", __func__,
+ printk("spi-imx %s: mode %d, %u bpw, %d hz\n", __func__,
spi->mode, spi->bits_per_word, spi->max_speed_hz);

if (spi->mode & SPI_NO_CS)
@@ -1632,6 +1632,7 @@ static int spi_imx_probe(struct platform_device *pdev)
(struct spi_imx_devtype_data *)pdev->id_entry->driver_data;
bool slave_mode;

+ printk("spi-imx probe called\n");
if (!np && !mxc_platform_info) {
dev_err(&pdev->dev, "can't get the platform data\n");
return -EINVAL;
@@ -1663,11 +1664,14 @@ static int spi_imx_probe(struct platform_device *pdev)
spi_imx->bitbang.master = master;
spi_imx->dev = &pdev->dev;
spi_imx->slave_mode = slave_mode;
+ printk("spi-imx slave-mode=%d\n", slave_mode);

spi_imx->devtype_data = devtype_data;

+ printk("spi-imx getting chip select\n");
/* Get number of chip selects, either platform data or OF */
if (mxc_platform_info) {
+ printk("spi-imx mxc platform inf is valid, getting chipselect\n");
master->num_chipselect = mxc_platform_info->num_chipselect;
if (mxc_platform_info->chipselect) {
master->cs_gpios = devm_kcalloc(&master->dev,
@@ -1681,9 +1685,11 @@ static int spi_imx_probe(struct platform_device *pdev)
}
} else {
u32 num_cs;
-
- if (!of_property_read_u32(np, "num-cs", &num_cs))
+ printk("spi-imx mxc platform info is invalid, getting cs of dts\n");
+ if (!of_property_read_u32(np, "num-cs", &num_cs)){
+ printk("spi-imx num-cs=%d", num_cs);
master->num_chipselect = num_cs;

+               }
                /* If not preset, default value of 1 is used */
        }

@@ -1704,6 +1710,7 @@ static int spi_imx_probe(struct platform_device *pdev)
        spi_imx->spi_drctl = spi_drctl;

        init_completion(&spi_imx->xfer_done);
+       printk("spi-imx init_completion done\n");

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        spi_imx->base = devm_ioremap_resource(&pdev->dev, res);
@@ -1766,14 +1773,11 @@ static int spi_imx_probe(struct platform_device *pdev)
        spi_imx->devtype_data->intctrl(spi_imx, 0);

        master->dev.of_node = pdev->dev.of_node;
-       ret = spi_bitbang_start(&spi_imx->bitbang);
-       if (ret) {
-               dev_err(&pdev->dev, "bitbang start failed with %d\n", ret);
-               goto out_clk_put;
-       }

        /* Request GPIO CS lines, if any */
+       printk("spi-imx request gpio cs lines\n");
        if (!spi_imx->slave_mode && master->cs_gpios) {
+               printk("spi-imx go through chip selects\n");
                for (i = 0; i < master->num_chipselect; i++) {
                        if (!gpio_is_valid(master->cs_gpios[i]))
                                continue;
@@ -1788,6 +1792,26 @@ static int spi_imx_probe(struct platform_device *pdev)
                        }
                }
        }
+       else{
+               printk("spi-imx slave mode on or master cs gpios unvalid\n");
+               printk("master->num_chipselect=%d\n", master->num_chipselect);
+               if(!spi_imx->slave_mode)
+                       printk("spi-imx slave mode is off");
+               else
+                       printk("spi-imx slave mode is on");
+               if(master->cs_gpios)
+                       printk("master-cs-gpios are valid");
+               else
+                       printk("master cs-gpios are not valid");
+       }
+
+       printk("spi-imx starting bitbang\n");
+       ret = spi_bitbang_start(&spi_imx->bitbang);
+       if (ret) {
+               dev_err(&pdev->dev, "bitbang start failed with %d\n", ret);
+               goto out_clk_put;
+       }

+

        dev_info(&pdev->dev, "probed\n");

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 26b91ee0855d..bc451b0ab265 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -775,6 +775,7 @@ int spi_register_board_info(struct spi_board_info const *info, unsigned n)

 static void spi_set_cs(struct spi_device *spi, bool enable)
 {
+       printk("spi_set_cs called\n");
        if (spi->mode & SPI_CS_HIGH)
                enable = !enable;

@@ -2245,10 +2246,12 @@ static int of_spi_get_gpio_numbers(struct spi_controller *ctlr)
        int nb, i, *cs;
        struct device_node *np = ctlr->dev.of_node;

+       printk("of_spi_get_gpio_numbers called\n");
        if (!np)
                return 0;

        nb = of_gpio_named_count(np, "cs-gpios");
+       printk("of_spi_get_gpio_numbers nb=%d\n", nb);
        ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);

        /* Return error only for an incorrectly formed cs-gpios property */
@@ -2267,8 +2270,10 @@ static int of_spi_get_gpio_numbers(struct spi_controller *ctlr)
        for (i = 0; i < ctlr->num_chipselect; i++)
                cs[i] = -ENOENT;

-       for (i = 0; i < nb; i++)
+       for (i = 0; i < nb; i++){
+               printk("of_spi getting named gpios\n");
                cs[i] = of_get_named_gpio(np, "cs-gpios", i);
+       }

        return 0;
 }
@@ -2385,6 +2390,7 @@ int spi_register_controller(struct spi_controller *ctlr)
        int                     status;
        int                     id, first_dynamic;

+       printk("spi register controller called\n");
        if (!dev)
                return -ENODEV;

--
2.17.1

When I start the Board and check the seriel output, I already see, that moving the gpio request to another place, is (if I understand that correctly) not the right option.

The output with the switch:

[    0.964689] spi-imx probe called
[    0.967935] spi-imx slave-mode=0
[    0.971168] spi-imx getting chip select
[    0.975008] spi-imx mxc platform info is invalid, getting cs of dts
[    0.981279] spi-imx init_completion done
[    0.985317] spi-imx request gpio cs lines
[    0.989333] spi-imx slave mode on or master cs gpios unvalid
[    0.994998] master->num_chipselect=1
[    0.998577] spi-imx slave mode is off
[    0.998579] master cs-gpios are not valid
[    1.002244] spi-imx starting bitbang
[    1.009835] spi register controller called
[    1.013945] of_spi_get_gpio_numbers called
[    1.018049] of_spi_get_gpio_numbers nb=1
[    1.021976] of_spi getting named gpios
[    1.025935] spi-imx spi_imx_setup: mode 4, 8 bpw, 10000000 hz
[    1.031736] spi_set_cs called
[    1.034843] ------------[ cut here ]------------
[    1.039470] /soc@0/bus@30800000/spi@30830000/spidev@0x00: buggy DT: spidev listed directly in DT
[    1.048300] WARNING: CPU: 0 PID: 1 at drivers/spi/spidev.c:723 spidev_probe+0x104/0x220
[    1.056300] Modules linked in:
[    1.059358] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.3-lts-lf-5.4.y+gf8118585ee3c #1
[    1.067531] Hardware name: NXP i.MX8MNano DDR4 EVK board (DT)
[    1.073275] pstate: 60000005 (nZCv daif -PAN -UAO)
[    1.078064] pc : spidev_probe+0x104/0x220
[    1.082071] lr : spidev_probe+0x104/0x220
[    1.086077] sp : ffff80001003b7d0
[    1.089389] x29: ffff80001003b7d0 x28: 0000000000000001
[    1.094700] x27: ffff000078aedb80 x26: ffff800011923330
[    1.100010] x25: 0000000000000000 x24: 0000000000000000
[    1.105320] x23: ffff800011932e60 x22: 0000000000000000
[    1.110631] x21: ffff800011932e40 x20: ffff00007868c800
[    1.115941] x19: 0000000000000000 x18: 0000000000000010
[    1.121252] x17: 00000000fd12cf85 x16: ffff000078006510
[    1.126562] x15: ffff000078090470 x14: 6c20766564697073
[    1.131873] x13: 203a544420796767 x12: 7562203a30307830
[    1.137183] x11: 407665646970732f x10: 3030303033383033
[    1.142493] x9 : 406970732f303030 x8 : ffff8000119e3000
[    1.147804] x7 : ffff80001067f5e8 x6 : 00000000000000d3
[    1.153114] x5 : 0000000000000000 x4 : 0000000000000000
[    1.158424] x3 : 00000000ffffffff x2 : ffff8000118d1520
[    1.163734] x1 : 77bee9e389fa8f00 x0 : 0000000000000000
[    1.169044] Call trace:
[    1.171490]  spidev_probe+0x104/0x220
[    1.175152]  spi_drv_probe+0x7c/0xd8
[    1.178728]  really_probe+0xd4/0x308
[    1.182303]  driver_probe_device+0x54/0xe8
[    1.186399]  __device_attach_driver+0x80/0xb8
[    1.190755]  bus_for_each_drv+0x74/0xc0
[    1.194589]  __device_attach+0xdc/0x138
[    1.198424]  device_initial_probe+0x10/0x18
[    1.202605]  bus_probe_device+0x90/0x98
[    1.206440]  device_add+0x378/0x648
[    1.209927]  spi_add_device+0xe4/0x1c8
[    1.213675]  of_register_spi_device+0x204/0x3c8
[    1.218204]  spi_register_controller+0x664/0x74c
[    1.222819]  spi_bitbang_start+0x34/0x80
[    1.226741]  spi_imx_probe+0x608/0x6f0
[    1.230489]  platform_drv_probe+0x50/0xa0
[    1.234498]  really_probe+0xd4/0x308
[    1.238072]  driver_probe_device+0x54/0xe8
[    1.242167]  device_driver_attach+0x6c/0x78
[    1.246349]  __driver_attach+0x54/0xd0
[    1.250097]  bus_for_each_dev+0x6c/0xc0
[    1.253931]  driver_attach+0x20/0x28
[    1.257506]  bus_add_driver+0x140/0x1e8
[    1.261340]  driver_register+0x60/0x110
[    1.265174]  __platform_driver_register+0x44/0x50
[    1.269879]  spi_imx_driver_init+0x1c/0x24
[    1.273975]  do_one_initcall+0x50/0x190
[    1.277811]  kernel_init_freeable+0x194/0x22c
[    1.282168]  kernel_init+0x10/0x100
[    1.285655]  ret_from_fork+0x10/0x18
[    1.289232] ---[ end trace de09230545766b9c ]---
[    1.293994] spi_imx 30830000.spi: probed

the output without it:

[    0.965239] spi-imx probe called
[    0.968486] spi-imx slave-mode=0
[    0.971719] spi-imx getting chip select
[    0.975558] spi-imx mxc platform info is invalid, getting cs of dts
[    0.981829] spi-imx init_completion done
[    0.985870] spi-imx spi bitbang start
[    0.989540] spi register controller called
[    0.993649] of_spi_get_gpio_numbers called
[    0.997752] of_spi_get_gpio_numbers nb=1
[    1.001682] of_spi getting named gpios
[    1.005641] spi-imx spi_imx_setup: mode 0, 8 bpw, 10000000 hz
[    1.011405] spi_set_cs called
[    1.014504] ------------[ cut here ]------------
[    1.019131] /soc@0/bus@30800000/spi@30830000/spidev@0x00: buggy DT: spidev listed directly in DT
[    1.027963] WARNING: CPU: 3 PID: 1 at drivers/spi/spidev.c:723 spidev_probe+0x104/0x220
[    1.035963] Modules linked in:
[    1.039020] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.4.3-lts-lf-5.4.y+gf8118585ee3c #1
[    1.047193] Hardware name: NXP i.MX8MNano DDR4 EVK board (DT)
[    1.052937] pstate: 60000005 (nZCv daif -PAN -UAO)
[    1.057726] pc : spidev_probe+0x104/0x220
[    1.061734] lr : spidev_probe+0x104/0x220
[    1.065739] sp : ffff80001003b7d0
[    1.069051] x29: ffff80001003b7d0 x28: 0000000000000001
[    1.074362] x27: ffff000078b88080 x26: ffff800011923330
[    1.079673] x25: 0000000000000000 x24: 0000000000000000
[    1.084983] x23: ffff800011932e60 x22: 0000000000000000
[    1.090294] x21: ffff800011932e40 x20: ffff000078385000
[    1.095604] x19: 0000000000000000 x18: 0000000000000010
[    1.100914] x17: 0000000000000001 x16: 0000000000000019
[    1.106224] x15: ffff000078090470 x14: 6c20766564697073
[    1.111534] x13: 203a544420796767 x12: 7562203a30307830
[    1.116845] x11: 407665646970732f x10: 3030303033383033
[    1.122155] x9 : 406970732f303030 x8 : ffff8000119e3000
[    1.127465] x7 : ffff80001067f5e8 x6 : 00000000000000ce
[    1.132776] x5 : 0000000000000000 x4 : 0000000000000000
[    1.138086] x3 : 00000000ffffffff x2 : ffff8000118d1520
[    1.143396] x1 : 9586de38223a3d00 x0 : 0000000000000000
[    1.148706] Call trace:
[    1.151152]  spidev_probe+0x104/0x220
[    1.154814]  spi_drv_probe+0x7c/0xd8
[    1.158390]  really_probe+0xd4/0x308
[    1.161965]  driver_probe_device+0x54/0xe8
[    1.166060]  __device_attach_driver+0x80/0xb8
[    1.170417]  bus_for_each_drv+0x74/0xc0
[    1.174252]  __device_attach+0xdc/0x138
[    1.178087]  device_initial_probe+0x10/0x18
[    1.182269]  bus_probe_device+0x90/0x98
[    1.186103]  device_add+0x378/0x648
[    1.189591]  spi_add_device+0xe4/0x1c8
[    1.193339]  of_register_spi_device+0x204/0x3c8
[    1.197869]  spi_register_controller+0x664/0x74c
[    1.202484]  spi_bitbang_start+0x34/0x80
[    1.206407]  spi_imx_probe+0x500/0x6f8
[    1.210155]  platform_drv_probe+0x50/0xa0
[    1.214163]  really_probe+0xd4/0x308
[    1.217737]  driver_probe_device+0x54/0xe8
[    1.221832]  device_driver_attach+0x6c/0x78
[    1.226014]  __driver_attach+0x54/0xd0
[    1.229762]  bus_for_each_dev+0x6c/0xc0
[    1.233597]  driver_attach+0x20/0x28
[    1.237171]  bus_add_driver+0x140/0x1e8
[    1.241005]  driver_register+0x60/0x110
[    1.244839]  __platform_driver_register+0x44/0x50
[    1.249544]  spi_imx_driver_init+0x1c/0x24
[    1.253640]  do_one_initcall+0x50/0x190
[    1.257476]  kernel_init_freeable+0x194/0x22c
[    1.261833]  kernel_init+0x10/0x100
[    1.265320]  ret_from_fork+0x10/0x18
[    1.268898] ---[ end trace b6ad49a34d072e58 ]---
[    1.273651] spi-imx request gpio cs lines
[    1.277667] spi-imx go through chip selects
[    1.281860] spi_imx 30830000.spi: probed

sorry, it is not pretty and the english is bad.

the thing is, that when I switch the place for the gpio_request, there are no master->cs_gpios created and the function

if (!spi_imx->slave_mode && master->cs_gpios) {

will always be evaluated as "no"

In both cases, the CS is not toggled. It remains low infinitely.

I will try to reproduce the behaviour with another board and let you know, if I find out anything.