Early console patch for iMX 3.1x kernel to print debug messages from debug UART port

Document created by Qiang Li - Mpu Se Employee on Jun 27, 2016Last modified by Qiang Li - Mpu Se Employee on Feb 21, 2020
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From iMX 3.1x kernel, all kernel debug messages will be print to debug serial port after UART driver loaded, so if the kernel hang up before tty console driver ready, there will be no kernel boot up messages.


The attached patch can be used to enable the iMX serial debug console in early time, then kernel will not buffer the debug messages.


Note: the default patch is for UART1 (tty0) as the debug port, if you need use other debug port, please modify the code "early_console_setup()" with correct UART port base address.



This patch is based on L3.10.53_GA1.1.0 release, it can support iMX6S/DL/D/Q.



This patch is based on L3.14.52_GA1.1.0 release, it can support iMX6S/DL/D/Q, iMX6SL, iMX6SX, iMX6UL and iMX7.



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