[PATCH] ppc64: Fix __raw_* IO accessors

Benjamin Herrenschmidt
2004-09-21T09:26:22Z

Hi !

Linus, I don't know if you did that on purpose, but you removed the
"volatile" statement from the definition of the __raw_* IO accessors
on ppc64, which cause some real bad optisations to happen in some
fbdev's like matroxfb to happen (just imagine that matroxfb loops
reading an IO register waiting for a bit to change).

(Note: matroxfb has other potential problems due to the fact that
__raw_* do not do any barrier (Petr, we probably need to fix that
some way, unfortunatley, I don't think we have a good abstraction
for providing the missing barrier to a driver using __raw... can't
you just switch back to little endian registers and use normal
readX/writeX ?)

Anyway, here's the fix for asm-ppc64/io.h

Signed-off-by: Benjamin Herrenschmidt <benh@kenrel.crashing.org>

===== include/asm/io.h 1.21 vs edited =====
--- 1.21/include/asm-ppc64/io.h 2004-09-14 04:31:52 +10:00
+++ edited/include/asm/io.h 2004-09-21 19:14:10 +10:00
@@ -71,35 +71,35 @@

static inline unsigned char __raw_readb(const volatile void __iomem *addr)
{
- return *(unsigned char __force *)addr;
+ return *(volatile unsigned char __force *)addr;
}
static inline unsigned short __raw_readw(const volatile void __iomem *addr)
{
- return *(unsigned short __force *)addr;
+ return *(volatile unsigned short __force *)addr;
}
static inline unsigned int __raw_readl(const volatile void __iomem *addr)
{
- return *(unsigned int __force *)addr;
+ return *(volatile unsigned int __force *)addr;
}
static inline unsigned long __raw_readq(const volatile void __iomem *addr)
{
- return *(unsigned long __force *)addr;
+ return *(volatile unsigned long __force *)addr;
}
static inline void __raw_writeb(unsigned char v, volatile void __iomem *addr)
{
- *(unsigned char __force *)addr = v;
+ *(volatile unsigned char __force *)addr = v;
}
static inline void __raw_writew(unsigned short v, volatile void __iomem *addr)
{
- *(unsigned short __force *)addr = v;
+ *(volatile unsigned short __force *)addr = v;
}
static inline void __raw_writel(unsigned int v, volatile void __iomem *addr)
{
- *(unsigned int __force *)addr = v;
+ *(volatile unsigned int __force *)addr = v;
}
static inline void __raw_writeq(unsigned long v, volatile void __iomem *addr)
{
- *(unsigned long __force *)addr = v;
+ *(volatile unsigned long __force *)addr = v;
}
#define readb(addr) eeh_readb(addr)
#define readw(addr) eeh_readw(addr)