It doesn't work since the gtt pte range sits in the middle of the mmio
bar. We didn't notice that since both my and Chris' gen2 machines
don't support PAT and hence all wc io mapping request will
automatically be demoted to uc.
This regression has been introduce in
commit edef7e685da05c13cce50c0126189c80fe2c8f71
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Fri Sep 14 11:57:47 2012 +0100
agp/intel: Use a write-combining map for updating PTEs
Reported-by: Egbert Eich <eich at pdx.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=55834
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
drivers/char/agp/intel-gtt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index e01f5ea..38390f7 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -667,7 +667,7 @@ static int intel_gtt_init(void)
gtt_map_size = intel_private.base.gtt_total_entries * 4;
intel_private.gtt = NULL;
- if (INTEL_GTT_GEN < 6)
+ if (INTEL_GTT_GEN < 6 && INTEL_GTT_GEN > 2)
intel_private.gtt = ioremap_wc(intel_private.gtt_bus_addr,
gtt_map_size);
if (intel_private.gtt == NULL)
--
1.7.11.2
