From: Ralf Baechle <ralf@linux-mips.org>
Date: Fri, 27 Nov 2015 18:17:01 +0000 (+0100)
Subject: MIPS: Fix delay loops which may be removed by GCC.
X-Git-Tag: drm-fsl-dcu-for-next~2065^2
X-Git-Url: http://git.agner.ch/gitweb/?p=linux-drm-fsl-dcu.git;a=commitdiff_plain;h=c861519fcf95b2d46cb4275903423b43ae150a40

MIPS: Fix delay loops which may be removed by GCC.

GCC 4.1 and newer remove empty loops.  This becomes a problem when delay
loops get removed.  Fixed by rewriting to user the proper Linux interface
for such delays.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: John Crispin <blogic@openwrt.org>
---

diff --git a/arch/mips/pci/pci-rt2880.c b/arch/mips/pci/pci-rt2880.c
index 8a978022630b..dbbeccc3d714 100644
--- a/arch/mips/pci/pci-rt2880.c
+++ b/arch/mips/pci/pci-rt2880.c
@@ -11,6 +11,7 @@
  *  by the Free Software Foundation.
  */
 
+#include <linux/delay.h>
 #include <linux/types.h>
 #include <linux/pci.h>
 #include <linux/io.h>
@@ -232,8 +233,7 @@ static int rt288x_pci_probe(struct platform_device *pdev)
 	ioport_resource.end = RT2880_PCI_IO_BASE + RT2880_PCI_IO_SIZE - 1;
 
 	rt2880_pci_reg_write(0, RT2880_PCI_REG_PCICFG_ADDR);
-	for (i = 0; i < 0xfffff; i++)
-		;
+	udelay(1);
 
 	rt2880_pci_reg_write(0x79, RT2880_PCI_REG_ARBCTL);
 	rt2880_pci_reg_write(0x07FF0001, RT2880_PCI_REG_BAR0SETUP_ADDR);
diff --git a/arch/mips/pmcs-msp71xx/msp_setup.c b/arch/mips/pmcs-msp71xx/msp_setup.c
index 4f925e06c414..78b2ef49dbc7 100644
--- a/arch/mips/pmcs-msp71xx/msp_setup.c
+++ b/arch/mips/pmcs-msp71xx/msp_setup.c
@@ -10,6 +10,8 @@
  * option) any later version.
  */
 
+#include <linux/delay.h>
+
 #include <asm/bootinfo.h>
 #include <asm/cacheflush.h>
 #include <asm/idle.h>
@@ -77,7 +79,7 @@ void msp7120_reset(void)
 	 */
 
 	/* Wait a bit for the DDRC to settle */
-	for (i = 0; i < 100000000; i++);
+	mdelay(125);
 
 #if defined(CONFIG_PMC_MSP7120_GW)
 	/*
diff --git a/arch/mips/sni/reset.c b/arch/mips/sni/reset.c
index 244f9427625b..db8f88b6a3af 100644
--- a/arch/mips/sni/reset.c
+++ b/arch/mips/sni/reset.c
@@ -3,6 +3,8 @@
  *
  *  Reset a SNI machine.
  */
+#include <linux/delay.h>
+
 #include <asm/io.h>
 #include <asm/reboot.h>
 #include <asm/sni.h>
@@ -32,9 +34,9 @@ void sni_machine_restart(char *command)
 	for (;;) {
 		for (i = 0; i < 100; i++) {
 			kb_wait();
-			for (j = 0; j < 100000 ; j++)
-				/* nothing */;
+			udelay(50);
 			outb_p(0xfe, 0x64);	 /* pulse reset low */
+			udelay(50);
 		}
 	}
 }