Hi Mr Nutt, I am so sorry for delaying my answer. I went into vacation and missed this conversation.
So, I came up to the conclusion that the *<chip>_lowsetup *function that I've seen in many chips is a standard deviation and it is actually playing the role of the *xyz_earlyserialinit().* Am I right? Thanks too much for the detailed explanation. Em qua., 10 de fev. de 2021 às 12:33, Gregory Nutt <spudan...@gmail.com> escreveu: > As I said, the early serial initialization is needed for boot-up debug > output. Here is a little more detail: > > If the serial is not initialized, then up_putc will not work. In fact, > any calls to up_putc() could hang. If the serial console is the syslog > debug channel, then up_putc is called from syslog under certain conditions: > > * Syslog output from an interrupt handler > * Syslog() is called with LOG_EMERG > * Syslog() is called early in the initialization (while using the > g_default_channel) > > up_putc is also used in most very low level startup logic in the > PROGRESS macro that outputs the ABCDEF that you see when booting most > NuttX systems. > > What happens if the serial device used by up_putc is not initialized? > It will certainly fail to ouput anything but could also hang on a busy > wait polling an uninitialized device. > > >
