From: Luigi Semenzato <semenzato@chromium.org>
Date: Wed, 27 Mar 2013 23:45:14 +0000 (-0700)
Subject: CHROMIUM: detect GPU memory mapped at < 1MB physaddr.
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=51f5eb1c0c5614e841e2adf7f504dda1e79298d9;p=cascardo%2Flinux.git

CHROMIUM: detect GPU memory mapped at < 1MB physaddr.

We want to check if we ever map GPU memory at < 1MB,
because of problems in Sandy Bridge (and possibly Ivy Bridge).

BUG=chromium:224320
TEST=compiled, booted
BRANCH=none

Change-Id: I731da19f2a4d5230f84b54dbfd3993a5cb8dfe72
Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/46716
---

diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index 7f025fb620de..eb2ace042b0d 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -913,6 +913,9 @@ void intel_gtt_insert_pages(unsigned int first_entry, unsigned int num_entries,
 		dma_addr_t addr = page_to_phys(pages[i]);
 		intel_private.driver->write_entry(addr,
 						  j, flags);
+		if (unlikely(addr < 1 << 20))
+			panic("gtt: using low address 0x%lx",
+			      (unsigned long) addr);
 	}
 	readl(intel_private.gtt+j-1);
 }