virgefb.c PATCH

[Roberto R. <rob...@te...>]

Hi,

I don't know why but precompiled kernels 2000814 and 20000927
don't start on my CyberstormPPC 604e@150; the screen goes
white and nothing happens. According to bootmesg the kernel
is launched.
I'm running APUS since the first days, and I'm not doing silly
errors: last boothack, correct options, etc...
No problem with 20000518.

A couple of weeks ago I downloaded the 2.2 CVS tree to
compile a kernel myself.
Well, my own-compiled kernel does start and run. Good.

But I found that the Virge (CV64/3D) console acceleration was
corrupted (but X didn't suffer any problems): something was wrong
with the blitting.

I compared the source with older versions and it was exactly
identical!
So I thought there was a compiler problem, and, yes, I was right.
I'm using gcc 2.95.2 (from LinuxPPC 2000), which reorders memory
access, and it's not a good thing if you reorder register writes.

I added a "-fno-scrict-aliasing" to CFLAGS in the main Makefile
and patched the virgefb.c driver to be more careful about register
access. Maybe I added too many mb(), but I really don't think they
could cause mesaurable speed degradation, so I chose to be on the
safe side.
Here's the patch:

--- virgefb.c_orig	Thu May 25 21:08:31 2000
+++ virgefb.c	Sun Nov 26 16:56:57 2000
@@ -51,18 +51,18 @@
 #if 1
 #define vgawb_3d(reg,dat) \
 	if (cv3d_on_zorro2) { \
-	*((unsigned char volatile *)((Cyber_vcode_switch_base) + 0x04)) = \
-	(0x01 & 0xffff); asm volatile ("nop"); \
+	mb(); *((unsigned char volatile *)((Cyber_vcode_switch_base) + 0x04)) = \
+	(0x01 & 0xffff); asm volatile ("nop"); mb(); \
 	} \
-	(*((unsigned char *)(CyberVGARegs + (reg ^ 3))) = dat); \
+	mb(); (*((unsigned char *)(CyberVGARegs + (reg ^ 3))) = dat); mb(); \
 	if (cv3d_on_zorro2) { \
-	*((unsigned char volatile *)((Cyber_vcode_switch_base) + 0x04)) = \
-	(0x02 & 0xffff); asm volatile ("nop"); \
+	mb(); *((unsigned char volatile *)((Cyber_vcode_switch_base) + 0x04)) = \
+	(0x02 & 0xffff); asm volatile ("nop"); mb(); \
 	}
 #define vgaww_3d(reg,dat) \
-                (*((unsigned word *)(CyberVGARegs + (reg ^ 2))) = swab16(dat))
+                mb(); (*((unsigned word *)(CyberVGARegs + (reg ^ 2))) = swab16(dat)); mb();
 #define vgawl_3d(reg,dat) \
-                (*((unsigned long *)(CyberVGARegs + reg)) = swab32(dat))
+                mb(); (*((unsigned long *)(CyberVGARegs + reg)) = swab32(dat)); mb();
 #else
      /*
       * Dunno why this doesn't work at the moment - we'll have to look at
@@ -80,18 +80,18 @@
       * We asume P5 mapped the big-endian version of these registers.
       */
 #define wb_3d(reg,dat) \
-                (*((unsigned char volatile *)(CyberRegs + reg)) = dat)
+                mb(); (*((unsigned char volatile *)(CyberRegs + reg)) = dat); mb();
 #define ww_3d(reg,dat) \
-                (*((unsigned word volatile *)(CyberRegs + reg)) = dat)
+                mb(); (*((unsigned word volatile *)(CyberRegs + reg)) = dat); mb();
 #define wl_3d(reg,dat) \
-                (*((unsigned long volatile *)(CyberRegs + reg)) = dat)
+                mb(); (*((unsigned long volatile *)(CyberRegs + reg)) = dat); mb();
 #define rl_3d(reg) \
-                (*((unsigned long volatile *)(CyberRegs + reg)))
+                (*((unsigned long volatile *)(CyberRegs + reg))); mb();
 
 #define Select_Zorro2_FrameBuffer(flag) \
 	do { \
-		*((unsigned char volatile *)((Cyber_vcode_switch_base) + 0x08)) = \
-		((flag * 0x40) & 0xffff); asm volatile ("nop"); \
+		mb(); *((unsigned char volatile *)((Cyber_vcode_switch_base) + 0x08)) = \
+		((flag * 0x40) & 0xffff); asm volatile ("nop"); mb(); \
 	} while (0)
 /*
  *	may be needed when we initialize the board?


Now, if only someone could add X acceleration and mode switching...

BTW, ide-doubler fails to detect the third and fourth IDE drives.
It tries, but gets garbage instead of the drive names.

-- 

 |||||||. |||||||.  *Roberto Ragusa* <rob...@te...>
 ||....|| ||....||    - electronic engineering student
 ||||||.. ||||||..    - Amiga user
 ||..||.. ||..||..    - satellite TV enthusiast
 ||....|| ||....||            (PGP public key available)