From 8a09e2674e7783f8e2a37fdf7a0e86f758ef863f Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 22 Dec 2010 11:37:09 +0000 Subject: [PATCH] agp/intel: Experiment with a 855GM GWB bit Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=27187 Signed-off-by: Chris Wilson --- drivers/char/agp/intel-agp.h | 1 + drivers/char/agp/intel-gtt.c | 26 ++++++++++++++++++++------ 2 files changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/char/agp/intel-agp.h b/drivers/char/agp/intel-agp.h index c195bfe..5feebe2 100644 --- a/drivers/char/agp/intel-agp.h +++ b/drivers/char/agp/intel-agp.h @@ -130,6 +130,7 @@ #define INTEL_GMCH_GMS_STOLEN_352M (0xd << 4) #define I915_IFPADDR 0x60 +#define I830_HIC 0x70 /* Intel 965G registers */ #define I965_MSAC 0x62 diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c index da81618..f3e63dbe 100644 --- a/drivers/char/agp/intel-gtt.c +++ b/drivers/char/agp/intel-gtt.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include "agp.h" #include "intel-agp.h" @@ -757,14 +758,27 @@ static void intel_i830_setup_flush(void) */ static void i830_chipset_flush(void) { - unsigned int *pg = intel_private.i8xx_flush_page; + unsigned long timeout = jiffies + msecs_to_jiffies(1000); - memset(pg, 0, 1024); + /* Forcibly evict everything from the CPU write buffers. + * clflush appears to be insufficient. + */ + wbinvd_on_all_cpus(); + + /* Now we've only seen documents for this magic bit on 855GM, + * we hope it exists for the other gen2 chipsets... + * + * Also works as advertised on my 845G. + */ + writel(readl(intel_private.registers+I830_HIC) | (1<<31), + intel_private.registers+I830_HIC); - if (cpu_has_clflush) - clflush_cache_range(pg, 1024); - else if (wbinvd_on_all_cpus() != 0) - printk(KERN_ERR "Timed out waiting for cache flush.\n"); + while (readl(intel_private.registers+I830_HIC) & (1<<31)) { + if (time_after(jiffies, timeout)) + break; + + udelay(50); + } } static void i830_write_entry(dma_addr_t addr, unsigned int entry, -- 1.7.2.3