agp/intel: Reduce extraneous PCI posting reads during init

Instead of doing a posting read after each GTT entry update, do a single one
at the end of the writes. This should reduce boot time a tiny amount by
avoiding a lot of extra uncached reads.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
index f1fe74901314..81f094244471 100644
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -214,8 +214,8 @@ static int intel_i810_configure(void)
         if (agp_bridge->driver->needs_scratch_page) {
                 for (i = 0; i < current_size->num_entries; i++) {
                         writel(agp_bridge->scratch_page, intel_private.registers+I810_PTE_BASE+(i*4));
-                        readl(intel_private.registers+I810_PTE_BASE+(i*4));     /* PCI posting. */
                 }
+                readl(intel_private.registers+I810_PTE_BASE+((i-1)*4)); /* PCI posting. */
         }
         global_cache_flush();
         return 0;
@@ -775,8 +775,8 @@ static int intel_i830_configure(void)
         if (agp_bridge->driver->needs_scratch_page) {
                 for (i = intel_private.gtt_entries; i < current_size->num_entries; i++) {
                         writel(agp_bridge->scratch_page, intel_private.registers+I810_PTE_BASE+(i*4));
-                        readl(intel_private.registers+I810_PTE_BASE+(i*4));     /* PCI Posting. */
                 }
+                readl(intel_private.registers+I810_PTE_BASE+((i-1)*4)); /* PCI Posting. */
         }
 
         global_cache_flush();
@@ -991,8 +991,8 @@ static int intel_i915_configure(void)
         if (agp_bridge->driver->needs_scratch_page) {
                 for (i = intel_private.gtt_entries; i < current_size->num_entries; i++) {
                         writel(agp_bridge->scratch_page, intel_private.gtt+i);
-                        readl(intel_private.gtt+i);     /* PCI Posting. */
                 }
+                readl(intel_private.gtt+i-1);   /* PCI Posting. */
         }
 
         global_cache_flush();