agp/intel-agp: Clear entire GTT on startup
Some BIOSes fail to initialise the GTT, which will cause DMA faults when
the IOMMU is enabled. We need to clear the whole thing to point at the
scratch page, not just the part that Linux is going to use.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
[anholt: Note that this may also help with stability in the presence of
driver bugs, by not drawing to memory we don't own]
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
index 37cb4e2..33b4853 100644
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -176,6 +176,7 @@
* popup and for the GTT.
*/
int gtt_entries; /* i830+ */
+ int gtt_total_size;
union {
void __iomem *i9xx_flush_page;
void *i8xx_flush_page;
@@ -1151,7 +1152,7 @@
readl(intel_private.registers+I810_PGETBL_CTL); /* PCI Posting. */
if (agp_bridge->driver->needs_scratch_page) {
- for (i = intel_private.gtt_entries; i < current_size->num_entries; i++) {
+ for (i = intel_private.gtt_entries; i < intel_private.gtt_total_size; i++) {
writel(agp_bridge->scratch_page, intel_private.gtt+i);
}
readl(intel_private.gtt+i-1); /* PCI Posting. */
@@ -1312,6 +1313,8 @@
if (!intel_private.gtt)
return -ENOMEM;
+ intel_private.gtt_total_size = gtt_map_size / 4;
+
temp &= 0xfff80000;
intel_private.registers = ioremap(temp, 128 * 4096);
@@ -1398,6 +1401,8 @@
if (!intel_private.gtt)
return -ENOMEM;
+ intel_private.gtt_total_size = gtt_size / 4;
+
intel_private.registers = ioremap(temp, 128 * 4096);
if (!intel_private.registers) {
iounmap(intel_private.gtt);
