Daniel requested in the bug that I use a 3GB fallback size. Since this
is not in the spec as a valid size, I decided against it. We could
potentially add a patch to bump it to 3GB on top of this one.

This probably should be CC: stable - but I'll let the powers that be
decide that one.

Regression from a revert of the revert:
commit 7907f45bf9f67a1c5e5d4ae05bab428d7c2f43b2
Author: Ben Widawsky <[email protected]>
Date:   Wed Feb 19 22:05:46 2014 -0800

    Revert "drm/i915/bdw: Limit GTT to 2GB"

v2: Change ifdef to 32b, instead of ifndef
update comment

v3. Update comment to not wrap (Daniel).
Update commit message

v4: s/CONFIG_32/CONFIG_X86_32 (Jani).

v5: s/CONFIG_x86_32BIT/CONFIG_x86_32, as meant in v4
s/32B/32b (chris)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76619
Cc: [email protected]
Reviewed-by: Daniel Vetter <[email protected]>
Signed-off-by: Rodrigo Vivi <[email protected]>
Signed-off-by: Ben Widawsky <[email protected]>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c 
b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 931b906..eec820a 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1775,6 +1775,13 @@ static inline unsigned int gen8_get_total_gtt_size(u16 
bdw_gmch_ctl)
        bdw_gmch_ctl &= BDW_GMCH_GGMS_MASK;
        if (bdw_gmch_ctl)
                bdw_gmch_ctl = 1 << bdw_gmch_ctl;
+
+#ifdef CONFIG_X86_32
+       /* Limit 32b platforms to a 2GB GGTT: 4 << 20 / pte size * PAGE_SIZE */
+       if (bdw_gmch_ctl > 4)
+               bdw_gmch_ctl = 4;
+#endif
+
        return bdw_gmch_ctl << 20;
 }
 
-- 
1.9.3

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