From: Tim Gardner <tim.gardner@canonical.com>
Date: Fri, 9 Jul 2010 20:48:50 +0000 (-0600)
Subject: agp/intel: Use the correct mask to detect i830 aperture size.
X-Git-Tag: v2.6.35~33^2~4
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=e7b96f28c58ca09f15f6c2e8ccbb889a30fab4f7
 
agp/intel: Use the correct mask to detect i830 aperture size.
 
BugLink: https://bugs.launchpad.net/bugs/597075
 
commit f1befe71fa7a79ab733011b045639d8d809924ad 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 <tim.gardner@canonical.com>
Tested-by: Kees Cook <kees.cook@canonical.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Eric Anholt <eric@anholt.net>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
---
 
diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index 9344216..a754715 100644
--- 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 {