2 files changed, 50 insertions, 23 deletions

diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
index 883a36a27833..3491d6f84bc6 100644
--- a/drivers/char/agp/generic.c
+++ b/drivers/char/agp/generic.c
@@ -965,6 +965,9 @@ int agp_generic_insert_memory(struct agp_memory * mem, off_t pg_start, int type)
         if (!bridge)
                 return -EINVAL;
 
+        if (mem->page_count == 0)
+                return 0;
+
         temp = bridge->current_size;
 
         switch (bridge->driver->size_type) {
@@ -1016,8 +1019,8 @@ int agp_generic_insert_memory(struct agp_memory * mem, off_t pg_start, int type)
 
         for (i = 0, j = pg_start; i < mem->page_count; i++, j++) {
                 writel(bridge->driver->mask_memory(bridge, mem->memory[i], mem->type), bridge->gatt_table+j);
-                readl(bridge->gatt_table+j);    /* PCI Posting. */
         }
+        readl(bridge->gatt_table+j-1);  /* PCI Posting. */
 
         bridge->driver->tlb_flush(mem);
         return 0;
@@ -1034,6 +1037,9 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type)
         if (!bridge)
                 return -EINVAL;
 
+        if (mem->page_count == 0)
+                return 0;
+
         if (type != 0 || mem->type != 0) {
                 /* The generic routines know nothing of memory types */
                 return -EINVAL;
@@ -1042,10 +1048,9 @@ int agp_generic_remove_memory(struct agp_memory *mem, off_t pg_start, int type)
         /* AK: bogus, should encode addresses > 4GB */
         for (i = pg_start; i < (mem->page_count + pg_start); i++) {
                 writel(bridge->scratch_page, bridge->gatt_table+i);
-                readl(bridge->gatt_table+i);    /* PCI Posting. */
         }
+        readl(bridge->gatt_table+i-1);  /* PCI Posting. */
 
-        global_cache_flush();
         bridge->driver->tlb_flush(mem);
         return 0;
 }
diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
index 555b3a8ab49c..029d7f697567 100644
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -207,6 +207,9 @@ static int intel_i810_insert_entries(struct agp_memory *mem, off_t pg_start,
         int i, j, num_entries;
         void *temp;
 
+        if (mem->page_count == 0)
+                return 0;
+
         temp = agp_bridge->current_size;
         num_entries = A_SIZE_FIX(temp)->num_entries;
 
@@ -221,12 +224,16 @@ static int intel_i810_insert_entries(struct agp_memory *mem, off_t pg_start,
         if (type != 0 || mem->type != 0) {
                 if ((type == AGP_DCACHE_MEMORY) && (mem->type == AGP_DCACHE_MEMORY)) {
                         /* special insert */
-                        global_cache_flush();
+                        if (!mem->is_flushed) {
+                                global_cache_flush();
+                                mem->is_flushed = TRUE;
+                        }
+
                         for (i = pg_start; i < (pg_start + mem->page_count); i++) {
                                 writel((i*4096)|I810_PTE_LOCAL|I810_PTE_VALID, intel_i810_private.registers+I810_PTE_BASE+(i*4));
-                                readl(intel_i810_private.registers+I810_PTE_BASE+(i*4));        /* PCI Posting. */
                         }
-                        global_cache_flush();
+                        readl(intel_i810_private.registers+I810_PTE_BASE+((i-1)*4));    /* PCI Posting. */
+
                         agp_bridge->driver->tlb_flush(mem);
                         return 0;
                 }
@@ -236,14 +243,17 @@ static int intel_i810_insert_entries(struct agp_memory *mem, off_t pg_start,
         }
 
 insert:
-        global_cache_flush();
+        if (!mem->is_flushed) {
+                global_cache_flush();
+                mem->is_flushed = TRUE;
+        }
+
         for (i = 0, j = pg_start; i < mem->page_count; i++, j++) {
                 writel(agp_bridge->driver->mask_memory(agp_bridge,
                         mem->memory[i], mem->type),
                         intel_i810_private.registers+I810_PTE_BASE+(j*4));
-                readl(intel_i810_private.registers+I810_PTE_BASE+(j*4));        /* PCI Posting. */
         }
-        global_cache_flush();
+        readl(intel_i810_private.registers+I810_PTE_BASE+(j-1*4));      /* PCI Posting. */
 
         agp_bridge->driver->tlb_flush(mem);
         return 0;
@@ -254,12 +264,14 @@ static int intel_i810_remove_entries(struct agp_memory *mem, off_t pg_start,
 {
         int i;
 
+        if (mem->page_count == 0)
+                return 0;
+
         for (i = pg_start; i < (mem->page_count + pg_start); i++) {
                 writel(agp_bridge->scratch_page, intel_i810_private.registers+I810_PTE_BASE+(i*4));
-                readl(intel_i810_private.registers+I810_PTE_BASE+(i*4));        /* PCI Posting. */
         }
+        readl(intel_i810_private.registers+I810_PTE_BASE+((i-1)*4));
 
-        global_cache_flush();
         agp_bridge->driver->tlb_flush(mem);
         return 0;
 }
@@ -576,6 +588,9 @@ static int intel_i830_insert_entries(struct agp_memory *mem,off_t pg_start, int
         int i,j,num_entries;
         void *temp;
 
+        if (mem->page_count == 0)
+                return 0;
+
         temp = agp_bridge->current_size;
         num_entries = A_SIZE_FIX(temp)->num_entries;
 
@@ -598,16 +613,18 @@ static int intel_i830_insert_entries(struct agp_memory *mem,off_t pg_start, int
                 (mem->type != 0 && mem->type != AGP_PHYS_MEMORY))
                 return -EINVAL;
 
-        global_cache_flush();   /* FIXME: Necessary ?*/
+        if (!mem->is_flushed) {
+                global_cache_flush();
+                mem->is_flushed = TRUE;
+        }
 
         for (i = 0, j = pg_start; i < mem->page_count; i++, j++) {
                 writel(agp_bridge->driver->mask_memory(agp_bridge,
                         mem->memory[i], mem->type),
                         intel_i830_private.registers+I810_PTE_BASE+(j*4));
-                readl(intel_i830_private.registers+I810_PTE_BASE+(j*4));        /* PCI Posting. */
         }
+        readl(intel_i830_private.registers+I810_PTE_BASE+((j-1)*4));
 
-        global_cache_flush();
         agp_bridge->driver->tlb_flush(mem);
         return 0;
 }
@@ -617,7 +634,8 @@ static int intel_i830_remove_entries(struct agp_memory *mem,off_t pg_start,
 {
         int i;
 
-        global_cache_flush();
+        if (mem->page_count == 0)
+                return 0;
 
         if (pg_start < intel_i830_private.gtt_entries) {
                 printk (KERN_INFO PFX "Trying to disable local/stolen memory\n");
@@ -626,10 +644,9 @@ static int intel_i830_remove_entries(struct agp_memory *mem,off_t pg_start,
 
         for (i = pg_start; i < (mem->page_count + pg_start); i++) {
                 writel(agp_bridge->scratch_page, intel_i830_private.registers+I810_PTE_BASE+(i*4));
-                readl(intel_i830_private.registers+I810_PTE_BASE+(i*4));        /* PCI Posting. */
         }
+        readl(intel_i830_private.registers+I810_PTE_BASE+((i-1)*4));
 
-        global_cache_flush();
         agp_bridge->driver->tlb_flush(mem);
         return 0;
 }
@@ -686,6 +703,9 @@ static int intel_i915_insert_entries(struct agp_memory *mem,off_t pg_start,
         int i,j,num_entries;
         void *temp;
 
+        if (mem->page_count == 0)
+                return 0;
+
         temp = agp_bridge->current_size;
         num_entries = A_SIZE_FIX(temp)->num_entries;
 
@@ -708,15 +728,17 @@ static int intel_i915_insert_entries(struct agp_memory *mem,off_t pg_start,
                 (mem->type != 0 && mem->type != AGP_PHYS_MEMORY))
                 return -EINVAL;
 
-        global_cache_flush();
+        if (!mem->is_flushed) {
+                global_cache_flush();
+                mem->is_flushed = TRUE;
+        }
 
         for (i = 0, j = pg_start; i < mem->page_count; i++, j++) {
                 writel(agp_bridge->driver->mask_memory(agp_bridge,
                         mem->memory[i], mem->type), intel_i830_private.gtt+j);
-                readl(intel_i830_private.gtt+j);        /* PCI Posting. */
         }
+        readl(intel_i830_private.gtt+j-1);
 
-        global_cache_flush();
         agp_bridge->driver->tlb_flush(mem);
         return 0;
 }
@@ -726,7 +748,8 @@ static int intel_i915_remove_entries(struct agp_memory *mem,off_t pg_start,
 {
         int i;
 
-        global_cache_flush();
+        if (mem->page_count == 0)
+                return 0;
 
         if (pg_start < intel_i830_private.gtt_entries) {
                 printk (KERN_INFO PFX "Trying to disable local/stolen memory\n");
@@ -735,10 +758,9 @@ static int intel_i915_remove_entries(struct agp_memory *mem,off_t pg_start,
 
         for (i = pg_start; i < (mem->page_count + pg_start); i++) {
                 writel(agp_bridge->scratch_page, intel_i830_private.gtt+i);
-                readl(intel_i830_private.gtt+i);
         }
+        readl(intel_i830_private.gtt+i-1);
 
-        global_cache_flush();
         agp_bridge->driver->tlb_flush(mem);
         return 0;
 }