topic Re: unable to access some imx6ull registers from userspace using memtool or devmem2 in i.MX Processors

unable to access some imx6ull registers from userspace using memtool or devmem2

vemularamavarap — Wed, 17 Jun 2020 07:45:04 GMT

Dear I.MX Community,

I am using imx6ull for driving led matrix boards(used in railways) through spi interface, there i need to send huge data within a second for 100 times. But i achieved 40 times only through ioctl. So to improve the performance i need to access the spi registers directly through memtool or devmem2. But when i try to access spi registers virtual address is creating and then when i try to read the register board is not responding. But when i read the iomuxc (0x020E0000) it is reading successfully. So Please Provide the solution how to read spi registers from user space using memtool(i.e. through mmap) or devmem2 to achieve the required performance.

Below are the examples:

(iomuxc read successfully)

root@colibri-imx6ull:~# devmem2 0x20e0000
/dev/mem opened.
Memory mapped at address 0x76f23000.
Read at address 0x020E0000 (0x76f23000): 0x00000000

(ecspi1 read fail).

root@colibri-imx6ull:~# devmem2 0x2008000
/dev/mem opened.

*Not Displaying any thing after above statement and board is in hang state.

Kindly do the needful as early as possible.
Eagerly awaiting for your replies
Thanks in advance.

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

weidong_sun — Wed, 17 Jun 2020 09:32:45 GMT

Hi, vemula,

For all registers that drivers can access , memtool or devmem2 can also access them.

BUT the clock of the module where the register is located must be enabled, otherwise, corresponding registers can't be accessed.

Hope the information is helpful for you.

Have a nice day!

B.R,

Weidong

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

vemularamavarap — Wed, 17 Jun 2020 10:00:47 GMT

Thanks for reply. But I am new to processors and it's drivers.

So Please Provide how to enable clock for spi module(in spi_imx.c driver) of imx6ull. or Please provide the clock enabled spi driver.

Kindly do the needful as early as possible.

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

weidong_sun — Wed, 17 Jun 2020 10:27:40 GMT

Hi ,

Add spi node in device tree , setting it's status = "okay".

weidong

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

vemularamavarap — Wed, 17 Jun 2020 10:48:43 GMT

Hi,

Thanks For Reply.

That i have done and i have verified the spi clock frequency to 30 Mhz and spi data transfer also performed through ioctl system call using inbuilt driver but i am not achieving the performance. so i want to directly access the spi registers through devmem2 or memtool and want to transfer the data to achieve the required performance. But i am not able to access spi registers through memtool or devmem2.

I have Enabled below two SPI.

root@colibri-imx6ull:~# ls /dev/spidev*.*
/dev/spidev0.0 /dev/spidev2.0

Dts file for Reference:

&ecspi1 {
status = "okay";

   mcp251x0: mcp251x@0 {
       compatible = "microchip,mcp2515";
       pinctrl-names = "default";
       pinctrl-0 = <&pinctrl_can_int>;
       reg = <0>;
       clocks = <&clk16m>;
       interrupt-parent = <&gpio2>;
       interrupts = <4 IRQ_TYPE_EDGE_FALLING>;
       spi-max-frequency = <10000000>;
       //status = "okay";
                status = "disabled";
   };

   spidev0: spidev@0 {
       compatible = "toradex,evalspi";
       reg = <0>;
       spi-max-frequency = <60000000>;
       //status = "disabled";
                status = "okay";
   };
};

&ecspi3{
   status = "okay";
   spidev2: spidev@0 {
       compatible = "toradex,evalspi";
       reg = <0>;
       spi-max-frequency = <60000000>;
       //status = "disabled";
         status = "okay";
   };
};

Kindly do the needful as early as possible.

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

weidong_sun — Thu, 18 Jun 2020 06:06:46 GMT

Hi,

The max speed of SPI in i.MX6UL is 52MHz, 60MHz setting is no valid.

weidong

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

vemularamavarap — Thu, 18 Jun 2020 11:09:14 GMT

Hi,

Even though i have changed SPI max speed to 52 Mhz same result came . unable to access SPI address(0x2008000) board is hanging.

root@colibri-imx6ull:~# devmem2 0x2008000
/dev/mem opened.

*Not Displaying any thing after above statement and board is in hang state.

Is any thing need to be modified in driver for imx6ull???

Since with imx7d i am able to read SPI Address(0x30630000) :

Log is below:

colibri-imx7-emmc login: root
Last login: Tue Oct 15 09:18:00 UTC 2019 on ttymxc0
root@colibri-imx7-emmc:~# devmem2 0x30630000
/dev/mem opened.
Memory mapped at address 0x76fb1000.
Read at address 0x30630000 (0x76fb1000): 0x00000000

Kindly provide the solution.

vara prasad

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

weidong_sun — Fri, 19 Jun 2020 01:43:31 GMT

Hello vemula,

See below, please!

0x200_8000 register is a read-only register, even if you access it, you can't write data to it.

Hope the infromation is helpful to you.

Have a nice day!

B.R,

Weidong

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

vemularamavarap — Fri, 19 Jun 2020 05:35:27 GMT

Hi,

Here My Query is unable to read the read-only register, and unable to read/write the read/write register.

So Please provide the solution how to access it via user space. or Any thing to be modified in driver(spi_imx.c) to access it in user space.

vara prasad

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

weidong_sun — Fri, 19 Jun 2020 09:24:15 GMT

Hi vemula ,

For spi driver, by default, it is in suspend mode, when it works, clock will be provided. If you can try it like this:

COMMENT these funtions like "unprepare clock" . Then try to access register.

I am not sure if devmem2 is OK, so use memtool to try it.

Hope the information is helpful to you.

Have a nice day!

B.R,

Weidong

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

weidong_sun — Fri, 19 Jun 2020 09:33:56 GMT

try to do like this:

----------------------------------------------

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c

index 91e32291c44e..00e092f2f4ff 100644

--- a/drivers/spi/spi-imx.c

+++ b/drivers/spi/spi-imx.c

@@ -1602,8 +1602,8 @@ spi_imx_unprepare_message(struct spi_master *master, struct spi_message *msg)

{

struct spi_imx_data *spi_imx = spi_master_get_devdata(master);

- clk_disable_unprepare(spi_imx->clk_ipg);

- clk_disable_unprepare(spi_imx->clk_per);

+ // clk_disable_unprepare(spi_imx->clk_ipg);

+ // clk_disable_unprepare(spi_imx->clk_per);

return 0;

}

@@ -1791,8 +1791,8 @@ static int spi_imx_probe(struct platform_device *pdev)

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

- clk_disable_unprepare(spi_imx->clk_ipg);

- clk_disable_unprepare(spi_imx->clk_per);

+ // clk_disable_unprepare(spi_imx->clk_ipg);

+ // clk_disable_unprepare(spi_imx->clk_per);

return ret;

-----------------------------------------

Weidong

Re: unable to access some imx6ull registers from userspace using memtool or devmem2

vemularamavarap — Fri, 19 Jun 2020 11:20:37 GMT

Thank you Very much, it is working.