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 7f025fb..eb2ace0 100644 (file)
--- 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);
 }