agp/intel: Use the correct mask to detect i830 aperture size.

BugLink: https://bugs.launchpad.net/bugs/597075 commit f1befe7 introduced a regression when detecting aperture size of some i915 adapters, e.g., those on the Intel Q35 chipset. The original report: https://bugzilla.kernel.org/show_bug.cgi?id=15733 The regression report: https://bugzilla.kernel.org/show_bug.cgi?id=16294 According to the specification found at http://intellinuxgraphics.org/VOL_1_graphics_core.pdf, the PCI config space register I830_GMCH_CTRL is a mirror of GMCH Graphics Control. The correct macro for isolating the aperture size bits is therefore I830_GMCH_GMS_MASK along with the attendant changes to the case statement. Signed-off-by: Tim Gardner <[email protected]> Tested-by: Kees Cook <[email protected]> Cc: Chris Wilson <[email protected]> Cc: Eric Anholt <[email protected]> Cc: Jesse Barnes <[email protected]> Signed-off-by: Eric Anholt <[email protected]>
RyanHsu · Jul 26, 2010 · e7b96f2 · e7b96f2
1 parent 9c928d1
commit e7b96f2
Showing 1 changed file with 8 additions and 5 deletions.
diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
@@ -1216,17 +1216,20 @@ static int intel_i915_get_gtt_size(void)
 
 		/* G33's GTT size defined in gmch_ctrl */
 		pci_read_config_word(agp_bridge->dev, I830_GMCH_CTRL, &gmch_ctrl);
-		switch (gmch_ctrl & G33_PGETBL_SIZE_MASK) {
-		case G33_PGETBL_SIZE_1M:
+		switch (gmch_ctrl & I830_GMCH_GMS_MASK) {
+		case I830_GMCH_GMS_STOLEN_512:
+			size = 512;
+			break;
+		case I830_GMCH_GMS_STOLEN_1024:
 			size = 1024;
 			break;
-		case G33_PGETBL_SIZE_2M:
-			size = 2048;
+		case I830_GMCH_GMS_STOLEN_8192:
+			size = 8*1024;
 			break;
 		default:
 			dev_info(&agp_bridge->dev->dev,
 				 "unknown page table size 0x%x, assuming 512KB\n",
-				(gmch_ctrl & G33_PGETBL_SIZE_MASK));
+				(gmch_ctrl & I830_GMCH_GMS_MASK));
 			size = 512;
 		}
 	} else {