From: Grant Likely <grant.likely@secretlab.ca>
Date: Tue, 23 Oct 2007 04:27:46 +0000 (+1000)
Subject: [POWERPC] Uartlite: speed up console output
X-Git-Tag: v2.6.24-rc3~175^2^2~6
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d6b698764084510fe6168bb5b650165dced03ae;p=linux-2.6

[POWERPC] Uartlite: speed up console output

Change the wait_tx routine to call cpu_relax() instead of udelay() to
reduce console output latency and test for the TXFULL bit instead of
TXEMPTY.  That way the FIFO doesn't need to by 100% flushed before
writing the next character.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
---

diff --git a/drivers/serial/uartlite.c b/drivers/serial/uartlite.c
index dfef83f149..a85f2d31a6 100644
--- a/drivers/serial/uartlite.c
+++ b/drivers/serial/uartlite.c
@@ -329,12 +329,14 @@ static struct uart_ops ulite_ops = {
 static void ulite_console_wait_tx(struct uart_port *port)
 {
 	int i;
+	u8 val;
 
-	/* wait up to 10ms for the character(s) to be sent */
-	for (i = 0; i < 10000; i++) {
-		if (readb(port->membase + ULITE_STATUS) & ULITE_STATUS_TXEMPTY)
+	/* Spin waiting for TX fifo to have space available */
+	for (i = 0; i < 100000; i++) {
+		val = readb(port->membase + ULITE_STATUS);
+		if ((val & ULITE_STATUS_TXFULL) == 0)
 			break;
-		udelay(1);
+		cpu_relax();
 	}
 }