Yet another 2.6.35 regression (AGP)? (resend)

Yet another 2.6.35 regression (AGP)? (resend)

[Woody Suwalski]

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I have found one system, where 2.6.35 does not work (as tested with rc3 
and rc4)
That Intel system has no problems in 2.6.33.x nor 2.6.34.0.

The problem seems to be in AGP - I can boot if I specify "agp=off" - but 
of course only in text mode...
There seems to be a hard lock-up, so the only way to show the crash is 
by picture 8-)

Since I do not build kernel on that machine, I did not do any bisect 
tests, however if someone is interested in digging deeper, I can try... 
Preferably a patch to try out ;-)

This bug seems to be different then 
https://bugzilla.kernel.org/show_bug.cgi?id=16179

Should it be blamed on BIOS (the conflict indicated just before the crash)?

Thanks, Woody

PS. Resending, as original post cc'd 
drivers_video-dri-intel@kernel-bugs.osdl.org, what seems to be bad...


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Re: Yet another 2.6.35 regression (AGP)? (resend)

[Tim Gardner]

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On 07/09/2010 09:00 AM, Woody Suwalski wrote:
> I have found one system, where 2.6.35 does not work (as tested with rc3
> and rc4)
> That Intel system has no problems in 2.6.33.x nor 2.6.34.0.
>
> The problem seems to be in AGP - I can boot if I specify "agp=off" - but
> of course only in text mode...
> There seems to be a hard lock-up, so the only way to show the crash is
> by picture 8-)
>
> Since I do not build kernel on that machine, I did not do any bisect
> tests, however if someone is interested in digging deeper, I can try...
> Preferably a patch to try out ;-)
>
> This bug seems to be different then
> https://bugzilla.kernel.org/show_bug.cgi?id=16179
>
> Should it be blamed on BIOS (the conflict indicated just before the crash)?
>
> Thanks, Woody
>
> PS. Resending, as original post cc'd
> drivers_video-dri-intel@kernel-bugs.osdl.org, what seems to be bad...
>

How about this patch? I'm waiting confirmation from another user, but 
your problem looks quite similar.

rtg
-- 
Tim Gardner tim.gardner@canonical.com

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>From 684925d4ba303f9e23b428831c2386f0203d6622 Mon Sep 17 00:00:00 2001
From: Tim Gardner <tim.gardner@canonical.com>
Date: Fri, 9 Jul 2010 11:14:41 -0600
Subject: [PATCH] i915: Use the correct mask to detect i830 aperture size.

BugLink: https://bugs.launchpad.net/bugs/597075

commit f1befe71fa7a79ab733011b045639d8d809924ad introduced a regression when
detecting aperture size of some i915 adapters, e.g., those on the
Intel Q35 shipset.

The original report: https://bugzilla.kernel.org/show_bug.cgi?id=15733
The regression report: https://bugzilla.kernel.org/show_bug.cgi?id=16294

According to the specification found at http://intellinuxgraphics.org/VOL_1_graphics_core.pdf,
the PCI config space register I830_GMCH_CTRL is a mirror of GMCH Graphics Control. The correct
macro for isolating the aperture size bits is therefore I830_GMCH_GMS_MASK along with the
attendant changes to the case statement.

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Eric Anholt <eric@anholt.net>
---
 drivers/char/agp/intel-gtt.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index 9344216..a754715 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -1216,17 +1216,20 @@ static int intel_i915_get_gtt_size(void)
 
 		/* G33's GTT size defined in gmch_ctrl */
 		pci_read_config_word(agp_bridge->dev, I830_GMCH_CTRL, &gmch_ctrl);
-		switch (gmch_ctrl & G33_PGETBL_SIZE_MASK) {
-		case G33_PGETBL_SIZE_1M:
+		switch (gmch_ctrl & I830_GMCH_GMS_MASK) {
+		case I830_GMCH_GMS_STOLEN_512:
+			size = 512;
+			break;
+		case I830_GMCH_GMS_STOLEN_1024:
 			size = 1024;
 			break;
-		case G33_PGETBL_SIZE_2M:
-			size = 2048;
+		case I830_GMCH_GMS_STOLEN_8192:
+			size = 8*1024;
 			break;
 		default:
 			dev_info(&agp_bridge->dev->dev,
 				 "unknown page table size 0x%x, assuming 512KB\n",
-				(gmch_ctrl & G33_PGETBL_SIZE_MASK));
+				(gmch_ctrl & I830_GMCH_GMS_MASK));
 			size = 512;
 		}
 	} else {
-- 
1.7.0.4