ignore cached memory flag in i965_write_entry()?

ignore cached memory flag in i965_write_entry()?

[Zhenyu Wang]

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Looks from a6963596a13e62f8e65b1cf3403a330ff2db407c, setting
GTT entry on i965-ish totally ignored cached memory flag?
That might break r/w consistent for pages like hw status.

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Open Source Technology Center, Intel ltd.

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Re: ignore cached memory flag in i965_write_entry()?

[Zhenyu Wang]

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On 2010.12.14 11:03:53 +0800, Zhenyu Wang wrote:
> 
> Looks from a6963596a13e62f8e65b1cf3403a330ff2db407c, setting
> GTT entry on i965-ish totally ignored cached memory flag?
> That might break r/w consistent for pages like hw status.
> 

This should recover that.

From ca8cca3ffe03353c4bacdb30d77ff9c10ff0e4e0 Mon Sep 17 00:00:00 2001
From: Zhenyu Wang <zhenyuw@linux.intel.com>
Date: Tue, 14 Dec 2010 11:17:32 +0800
Subject: [PATCH] agp/intel: Fix missed cached memory flags setting in GTT entry write

This fixes regression from a6963596a13e62f8e65b1cf3403a330ff2db407c,
that missed to set cached memory type in GTT entry.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
---
 drivers/char/agp/intel-gtt.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index 326ca2e..c7fe85d 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -1138,9 +1138,15 @@ static void i9xx_chipset_flush(void)
 static void i965_write_entry(dma_addr_t addr, unsigned int entry,
 			     unsigned int flags)
 {
+	int pte_flags = I810_PTE_VALID;
+
 	/* Shift high bits down */
 	addr |= (addr >> 28) & 0xf0;
-	writel(addr | I810_PTE_VALID, intel_private.gtt + entry);
+
+	if (flags == AGP_USER_CACHED_MEMORY)
+		pte_flags |= I830_PTE_SYSTEM_CACHED;
+
+	writel(addr | pte_flags, intel_private.gtt + entry);
 }
 
 static bool gen6_check_flags(unsigned int flags)
-- 
1.7.1

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Re: ignore cached memory flag in i965_write_entry()?

[Chris Wilson]

On Tue, 14 Dec 2010 13:02:50 +0800, Zhenyu Wang <zhenyuw@linux.intel.com> wrote:
> On 2010.12.14 11:03:53 +0800, Zhenyu Wang wrote:
> > 
> > Looks from a6963596a13e62f8e65b1cf3403a330ff2db407c, setting
> > GTT entry on i965-ish totally ignored cached memory flag?
> > That might break r/w consistent for pages like hw status.
> > 
> 
> This should recover that.

Nice catch. My fault, I should have spotted that when I applied the patch.
Thanks!
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre