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SubjectRe: [Linux-fbdev-devel] Re: [PATCH] fbdev: Fix IO access in rivafb
Date
On Tuesday 09 November 2004 04:13, Linus Torvalds wrote:
> On Tue, 9 Nov 2004, Antonino A. Daplas wrote:
> > In big endian machines, the read*/write* accessors do a byteswap for an
> > inherently little endian PCI bus. However, rivafb puts the hardwire in
> > big endian register access, thus the byteswap is not needed. So, instead
> > of read*/write*, use __raw_read*/__raw_write*.
>
> This fix should make the #ifdef CONFIG_PCC entirely superfluous afaik.

Ah, of course.

>
> The thing is, once riva does its HW accesses right, the special cases just
> go away. There's a reason we have abstractions..
>
> Does anybody have the hardware to test with?
>

I've asked Guido Guenther to test, might take a couple of days. I also
asked him if he can use the in/out_be* which is probably safer for ppc.
And the mb()'s scattered all over the driver may be removed.

Tony


In big endian machines, the read*/write* accessors do a byteswap for an
inherently little endian PCI bus. However, rivafb puts the hardwire in big
endian register access, thus the byteswap is not needed. So for 16- and
32-bit access, instead of read*/write*, use __raw_read*/__raw_write* for all
archs.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
---

diff -Nru a/drivers/video/riva/riva_hw.h b/drivers/video/riva/riva_hw.h
--- a/drivers/video/riva/riva_hw.h 2004-11-09 05:39:48 +08:00
+++ b/drivers/video/riva/riva_hw.h 2004-11-09 06:00:09 +08:00
@@ -73,18 +73,13 @@
/*
* HW access macros.
*/
-#if defined(__powerpc__)
#include <asm/io.h>
-#define NV_WR08(p,i,d) out_8(p+i, d)
-#define NV_RD08(p,i) in_8(p+i)
-#else
#define NV_WR08(p,i,d) (writeb((d), (u8 __iomem *)(p) + (i)))
#define NV_RD08(p,i) (readb((u8 __iomem *)(p) + (i)))
-#endif
-#define NV_WR16(p,i,d) (writew((d), (u16 __iomem *)(p) + (i)/2))
-#define NV_RD16(p,i) (readw((u16 __iomem *)(p) + (i)/2))
-#define NV_WR32(p,i,d) (writel((d), (u32 __iomem *)(p) + (i)/4))
-#define NV_RD32(p,i) (readl((u32 __iomem *)(p) + (i)/4))
+#define NV_WR16(p,i,d) (__raw_writew((d), (u16 __iomem *)(p) + (i)/2))
+#define NV_RD16(p,i) (__raw_readw((u16 __iomem *)(p) + (i)/2))
+#define NV_WR32(p,i,d) (__raw_writel((d), (u32 __iomem *)(p) + (i)/4))
+#define NV_RD32(p,i) (__raw_readl((u32 __iomem *)(p) + (i)/4))
#define VGA_WR08(p,i,d) NV_WR08(p,i,d)
#define VGA_RD08(p,i) NV_RD08(p,i)



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