[PATCH] Clean-up and bug fix for tdfxfb framebuffer size detection

Attached is a patch against 2.6.11.7 which tidies up the tdfxfb framebuffer
size detection code a little and fixes the broken support for Voodoo4/5
cards.  (I haven't tested this on a Voodoo5, however, because I don't have
the hardware).
Signed-off-by: Richard Drummond <evilrich@rcdrummond.net>
Cc: <linux-fbdev-devel@lists.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/video/tdfxfb.c

@@ -430,36 +430,35 @@ static void do_write_regs(struct fb_info *info, struct banshee_reg* reg)
 
 static unsigned long do_lfb_size(struct tdfx_par *par, unsigned short dev_id) 
 {
-	u32 draminit0 = 0;
-	u32 draminit1 = 0;
-	u32 miscinit1 = 0;
-	u32 lfbsize   = 0;
-	int sgram_p   = 0;
+	u32 draminit0;
+	u32 draminit1;
+	u32 miscinit1;
+
+	int num_chips;
+	int chip_size; /* in MB */
+	u32 lfbsize;
+	int has_sgram;
 
 	draminit0 = tdfx_inl(par, DRAMINIT0);  
 	draminit1 = tdfx_inl(par, DRAMINIT1);
 
-	if ((dev_id == PCI_DEVICE_ID_3DFX_BANSHEE) ||
-	    (dev_id == PCI_DEVICE_ID_3DFX_VOODOO3)) {             	 
-		sgram_p = (draminit1 & DRAMINIT1_MEM_SDRAM) ? 0 : 1;
+	num_chips = (draminit0 & DRAMINIT0_SGRAM_NUM) ? 8 : 4;
  
-	lfbsize = sgram_p ?
-		(((draminit0 & DRAMINIT0_SGRAM_NUM)  ? 2 : 1) * 
-		((draminit0 & DRAMINIT0_SGRAM_TYPE) ? 8 : 4) * 1024 * 1024) :
-		16 * 1024 * 1024;
+	if (dev_id < PCI_DEVICE_ID_3DFX_VOODOO5) {
+		/* Banshee/Voodoo3 */
+		has_sgram = draminit1 & DRAMINIT1_MEM_SDRAM;
+		chip_size = has_sgram ? ((draminit0 & DRAMINIT0_SGRAM_TYPE) ? 2 : 1)
+				      : 2;
 	} else {
 		/* Voodoo4/5 */
-		u32 chips, psize, banks;
-
-		chips = ((draminit0 & (1 << 26)) == 0) ? 4 : 8;
-		psize = 1 << ((draminit0 & 0x38000000) >> 28);
-		banks = ((draminit0 & (1 << 30)) == 0) ? 2 : 4;
-		lfbsize = chips * psize * banks;
-		lfbsize <<= 20;
+		has_sgram = 0;
+		chip_size = 1 << ((draminit0 & DRAMINIT0_SGRAM_TYPE_MASK) >> DRAMINIT0_SGRAM_TYPE_SHIFT);
 	}
-	/* disable block writes for SDRAM (why?) */
+	lfbsize = num_chips * chip_size * 1024 * 1024;
+
+	/* disable block writes for SDRAM */
 	miscinit1 = tdfx_inl(par, MISCINIT1);
-	miscinit1 |= sgram_p ? 0 : MISCINIT1_2DBLOCK_DIS;
+	miscinit1 |= has_sgram ? 0 : MISCINIT1_2DBLOCK_DIS;
 	miscinit1 |= MISCINIT1_CLUT_INV;
 
 	banshee_make_room(par, 1); 

include/video/tdfx.h

@@ -99,6 +99,8 @@
 #define MISCINIT1_2DBLOCK_DIS           BIT(15)
 #define DRAMINIT0_SGRAM_NUM             BIT(26)
 #define DRAMINIT0_SGRAM_TYPE            BIT(27)
+#define DRAMINIT0_SGRAM_TYPE_MASK       (BIT(27)|BIT(28)|BIT(29))
+#define DRAMINIT0_SGRAM_TYPE_SHIFT      27
 #define DRAMINIT1_MEM_SDRAM             BIT(30)
 #define VGAINIT0_VGA_DISABLE            BIT(0)
 #define VGAINIT0_EXT_TIMING             BIT(1)