[PATCH 2/3] posting-read-after-flush

Chris Wilson chris at chris-wilson.co.uk
Thu Dec 14 09:06:04 UTC 2017


---
 drivers/char/agp/intel-gtt.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index c6271ce250b3..6f0659245ab1 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -1105,8 +1105,11 @@ static void i9xx_cleanup(void)
 
 static void i9xx_chipset_flush(void)
 {
-	if (intel_private.i9xx_flush_page)
-		writel(1, intel_private.i9xx_flush_page);
+	if (!intel_private.i9xx_flush_page)
+		return;
+
+	writel(1, intel_private.i9xx_flush_page);
+	(void)readl(intel_private.i9xx_flush_page);
 }
 
 static void i965_write_entry(dma_addr_t addr,
-- 
2.15.1



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