[Intel-gfx] [PATCH] drm/i915: Read the Base of Stolen Memory for 915gm

[Chris Wilson]

Reading the cspec pays dividends once again, as I found the 'Base of
Stolen Memory' config register so that we can skip the fragile
computation from Top of Usable Draw and use the real value provided by
the BIOS.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_stolen.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 130d1db..7f1735c 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -72,13 +72,10 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev)
 	} else if (INTEL_INFO(dev)->gen > 3 || IS_G33(dev)) {
 		/* Read Graphics Base of Stolen Memory directly */
 		pci_read_config_dword(pdev, 0xA4, &base);
-#if 0
 	} else if (IS_GEN3(dev)) {
-		u8 val;
-		/* Stolen is immediately below Top of Low Usable DRAM */
-		pci_read_config_byte(pdev, 0x9c, &val);
-		base = val >> 3 << 27;
-		base -= dev_priv->mm.gtt->stolen_size;
+		/* Read D2:F0 Base of Stolen Memory directly */
+		pci_read_config_dword(dev->pdev, 0x5c, &base);
+#if 0
 	} else {
 		/* Stolen is immediately above Top of Memory */
 		base = max_low_pfn_mapped << PAGE_SHIFT;
-- 
1.7.10.4