Commit de880632 authored Oct 06, 2017 by Nicolas Pitre Committed by Russell King Oct 12, 2017

ARM: 8705/1: early_printk: use printascii() rather than printch()



With printch() the console messages are sent out one character at a time
which is agonizingly slow especially with semihosting as the whole trap
intercept, remote byte access, and system resume danse is performed for
every single character across a relatively slow remote debug connection.

Let's use printascii() to send a whole string at once. This is also going
to be more efficient, albeit to a quite lesser extent, with serial ports
as well.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

parent e11d1314

arch/arm/kernel/early_printk.c

+10 −6

Original line number	Diff line number	Diff line
		@@ -11,16 +11,20 @@
		#include <linux/kernel.h>
		#include <linux/console.h>
		#include <linux/init.h>
		#include <linux/string.h>

		extern void printch(int);
		extern void printascii(const char *);

		static void early_write(const char *s, unsigned n)
		{
		while (n-- > 0) {
		if (*s == '\n')
		printch('\r');
		printch(*s);
		s++;
		char buf[128];
		while (n) {
		unsigned l = min(n, sizeof(buf)-1);
		memcpy(buf, s, l);
		buf[l] = 0;
		s += l;
		n -= l;
		printascii(buf);
		}
		}