agp/intel: Reduce extraneous PCI posting reads during init

commit 44d494417278e49f5b42bd3ded1801b6d2254db8 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
index 32c8006d927da6c2001ea6379b55bbec97863df9..5eb23fa48bbf3ebb4bfb6c8993ff02ed2b221a65 100644 (file)
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -217,8 +217,8 @@ 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;
@@ -778,8 +778,8 @@ 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();
@@ -994,8 +994,8 @@ 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();