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path: root/drivers/char/agp/intel-agp.c
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Diffstat (limited to 'drivers/char/agp/intel-agp.c')
-rw-r--r--drivers/char/agp/intel-agp.c30
1 files changed, 23 insertions, 7 deletions
diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
index c1729171503..e8dc75fc33c 100644
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -682,23 +682,39 @@ static void intel_i830_setup_flush(void)
if (!intel_private.i8xx_page)
return;
- /* make page uncached */
- map_page_into_agp(intel_private.i8xx_page);
-
intel_private.i8xx_flush_page = kmap(intel_private.i8xx_page);
if (!intel_private.i8xx_flush_page)
intel_i830_fini_flush();
}
+static void
+do_wbinvd(void *null)
+{
+ wbinvd();
+}
+
+/* The chipset_flush interface needs to get data that has already been
+ * flushed out of the CPU all the way out to main memory, because the GPU
+ * doesn't snoop those buffers.
+ *
+ * The 8xx series doesn't have the same lovely interface for flushing the
+ * chipset write buffers that the later chips do. According to the 865
+ * specs, it's 64 octwords, or 1KB. So, to get those previous things in
+ * that buffer out, we just fill 1KB and clflush it out, on the assumption
+ * that it'll push whatever was in there out. It appears to work.
+ */
static void intel_i830_chipset_flush(struct agp_bridge_data *bridge)
{
unsigned int *pg = intel_private.i8xx_flush_page;
- int i;
- for (i = 0; i < 256; i += 2)
- *(pg + i) = i;
+ memset(pg, 0, 1024);
- wmb();
+ if (cpu_has_clflush) {
+ clflush_cache_range(pg, 1024);
+ } else {
+ if (on_each_cpu(do_wbinvd, NULL, 1) != 0)
+ printk(KERN_ERR "Timed out waiting for cache flush.\n");
+ }
}
/* The intel i830 automatically initializes the agp aperture during POST.