Attachment 33593 Details for Bug 26345 – Wait after memory barriers for the system memory to update

[patch] Wait after memory barriers for the system memory to update

0001-agp-intel-Force-a-delay-on-i830-i845-to-flush-memory.patch (text/plain), 1.52 KB, created by Chris Wilson on 2010-02-26 09:25:04 UTC

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Creator: Chris Wilson

Created: 2010-02-26 09:25:04 UTC

Size: 1.52 KB

patch

obsolete

>From 5ed1b3e4f53dfc0dfdaa6137cadabc14c05340dc Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Fri, 26 Feb 2010 17:19:39 +0000
>Subject: [PATCH] agp/intel: Force a delay on i830/i845 to flush memory
>
>Papers over:
>  http://bugs.freedesktop.org/show_bug.cgi?id=26345
>  Bug 26345 - [i845G] x11perf freeze
>
>The essence of the bug is that the GPU begins executing the batch buffer
>prior to it being flushed to main memory - despite the fact that we have
>multiple memory barriers before we write to and advance the ringbuffer.
>The only means so far of ensuring that the batch buffer is consistent is
>to wait for a sufficiently long time...
>
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/char/agp/intel-agp.c |    6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
>diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
>index e5ffefe..5b8a570 100644
>--- a/drivers/char/agp/intel-agp.c
>+++ b/drivers/char/agp/intel-agp.c
>@@ -8,6 +8,7 @@
> #include <linux/kernel.h>
> #include <linux/pagemap.h>
> #include <linux/agp_backend.h>
>+#include <linux/delay.h>
> #include "agp.h"
> 
> /*
>@@ -843,6 +844,11 @@ static void intel_i830_chipset_flush(struct agp_bridge_data *bridge)
> 		if (on_each_cpu(do_wbinvd, NULL, 1) != 0)
> 			printk(KERN_ERR "Timed out waiting for cache flush.\n");
> 	}
>+
>+	/* XXX not even memory barriers are sufficient to flush memory before the
>+	 * GPU tries to execute.
>+	 */
>+	msleep(10);
> }
> 
> /* The intel i830 automatically initializes the agp aperture during POST.
>-- 
>1.7.0
>

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Attachments on bug 26345: 32942 | 32947 | 33268 | 33269 | 33331 | 33345 | 33593 | 33750 | 33751 | 33752 | 33756 | 33760 | 33835 | 34016 | 34194 | 34220 | 34233 | 34239 | 34240 | 34429 | 34435 | 34436 | 34437 | 34499 | 34663 | 34664 | 34676 | 51401 | 53024

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