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

ralfbaechle · ralfbaechle · commit ae878615d7ce · 2015-11-27T19:46:39.000+01:00
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 &lt;ralf@linux-mips.org&gt;
Reported-by: Rasmus Villemoes &lt;linux@rasmusvillemoes.dk&gt;
Acked-by: John Crispin &lt;blogic@openwrt.org&gt;
diff --git 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>
@@ -220,7 +221,6 @@ int __init pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
 static int rt288x_pci_probe(struct platform_device *pdev)
 {
 	void __iomem *io_map_base;
-	int i;
 
 	rt2880_pci_base = ioremap_nocache(RT2880_PCI_BASE, PAGE_SIZE);
 
@@ -232,8 +232,7 @@ 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
@@ -10,6 +10,8 @@
  * option) any later version.
  */
 
+#include <linux/delay.h>
+
 #include <asm/bootinfo.h>
 #include <asm/cacheflush.h>
 #include <asm/idle.h>
@@ -37,7 +39,6 @@ extern void msp_serial_setup(void);
 void msp7120_reset(void)
 {
 	void *start, *end, *iptr;
-	register int i;
 
 	/* Diasble all interrupts */
 	local_irq_disable();
@@ -77,7 +78,7 @@ 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
@@ -3,6 +3,8 @@
  *
  *  Reset a SNI machine.
  */
+#include <linux/delay.h>
+
 #include <asm/io.h>
 #include <asm/reboot.h>
 #include <asm/sni.h>
@@ -24,17 +26,17 @@ static inline void kb_wait(void)
 /* XXX This ends up at the ARC firmware prompt ...  */
 void sni_machine_restart(char *command)
 {
-	int i, j;
+	int i;
 
 	/* This does a normal via the keyboard controller like a PC.
 	   We can do that easier ...  */
 	local_irq_disable();
 	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);
 		}
 	}
 }

Original file line number	Diff line number	Diff line change
`@@ -3,6 +3,8 @@`
`3`	`3`	`*`
`4`	`4`	`* Reset a SNI machine.`
`5`	`5`	`*/`
	`6`	`+#include <linux/delay.h>`
	`7`	`+`
`6`	`8`	`#include <asm/io.h>`
`7`	`9`	`#include <asm/reboot.h>`
`8`	`10`	`#include <asm/sni.h>`
`@@ -24,17 +26,17 @@ static inline void kb_wait(void)`
`24`	`26`	`/* XXX This ends up at the ARC firmware prompt ... */`
`25`	`27`	`void sni_machine_restart(char *command)`
`26`	`28`	`{`
`27`		`- int i, j;`
	`29`	`+ int i;`
`28`	`30`
`29`	`31`	`/* This does a normal via the keyboard controller like a PC.`
`30`	`32`	`We can do that easier ... */`
`31`	`33`	`local_irq_disable();`
`32`	`34`	`for (;;) {`
`33`	`35`	`for (i = 0; i < 100; i++) {`
`34`	`36`	`kb_wait();`
`35`		`- for (j = 0; j < 100000 ; j++)`
`36`		`- /* nothing */;`
	`37`	`+ udelay(50);`
`37`	`38`	`outb_p(0xfe, 0x64); /* pulse reset low */`
	`39`	`+ udelay(50);`
`38`	`40`	`}`
`39`	`41`	`}`
`40`	`42`	`}`