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i.MX6Dual freezes during reboot with the SD card inserted

Question asked by Shibusawa on May 19, 2017
Latest reply on May 24, 2017 by Shibusawa

Dear Sir

 

I want to ask the behavior of i.MX6Dual.

The i.MX6Dual works on Android kk4.4.2_1.0.0-ga.

The i.MX6Dual freezes during reboot with the SD card inserted.

Reproducibility is about 5/10000.

 

There is a disable function(int __init mxc_early_uart_console_disable) in kernel_imx/drivers/tty/serial/mxc_uart_early.c.

 

int __init mxc_early_uart_console_disable(void)

{

              struct mxc_early_uart_device *device = &mxc_early_device;

              struct uart_port *port = &device->port;

 

              if (mxc_early_uart_console.index >= 0) {

                            unregister_console(&mxc_early_uart_console);

                            iounmap(port->membase);

                            clk_disable(device->clk);

                            clk_put(device->clk);

              }

              return 0;

}

 

It seems that the above function is called from do_initcalls() in kernel.

 

late_initcall_sync(mxc_early_uart_console_disable);

 

It seems that the problem will not occur when Commenting out the disable functions as the follows.

 

//unregister_console(&mxc_early_uart_console);

//iounmap(port->membase);

//clk_disable(device->clk);

//clk_put(device->clk);

 

It seems that the problem will occur if the clk_disable is enable as the follows.

//unregister_console(&mxc_early_uart_console);

//iounmap(port->membase);

clk_disable(device->clk);

//clk_put(device->clk);

 

Q1.

For what reason does it disable the uart?

 

Q2.

Are there any problem when Commenting out the disable functions as the follows.

//unregister_console(&mxc_early_uart_console);

//iounmap(port->membase);

//clk_disable(device->clk);

//clk_put(device->clk);

 

It seems that the uart is enable again later.

Q3.

What is it running between from uart disable to enable?

(We want to know what function is affected by commenting out these function.)

 

Best Regards,

Eishi SHIBUSAWA

 

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