linux-kernel - Re: 2.6.20-rc7 regression on intel-agp

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Message-ID: <20070204171850.GA17171@redhat.com>
Date:	Sun, 4 Feb 2007 12:18:50 -0500
From:	Dave Jones <davej@...hat.com>
To:	Eric Piel <Eric.Piel@...mplin-utc.net>
Cc:	Wang Zhenyu <zhenyu.z.wang@...el.com>,
	linux-kernel@...r.kernel.org, Adrian Bunk <bunk@...sta.de>
Subject: Re: 2.6.20-rc7 regression on intel-agp

On Sun, Feb 04, 2007 at 04:51:38PM +0100, Eric Piel wrote:
 > Hello,
 > 
 > I've got a regression in 2.6.20-rc7 (-rc6 was fine) due to commit 
 > 4b95320fc4d21b0ff2f8604305dd6c851aff6096 ([AGPGART] intel_agp: restore 
 > graphics device's pci space early in resume).

I think the key to this failure is the last line here ..

 > agpgart-intel 0000:00:00.0: resuming
 > PM: Writing back config space on device 0000:00:02.0 at offset f (was 10b, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset d (was dc, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset b (was 10161025, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset 5 (was f4000000, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset 4 (was f8000008, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset 2 (was 3000011, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset 1 (was 2b00007, writing 0)
 > PM: Writing back config space on device 0000:00:02.0 at offset 0 (was 11328086, writing 0)
 > agpgart: Unable to remap memory.

This then blows up the next access to intel_i810_private.registers, which happens to
be intel_i810_insert_entries.

Either we need .suspend methods which unmap these regions, or we need
to skip trying to map them a second time on resume.

There's an ugly patch below which does the latter. Give it a try?

The intel-agp suspend/resume code has really grown into something
of a monster, and could use some refactoring in a big way.

		Dave

diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
index a3011de..84787ce 100644
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -117,13 +117,15 @@ static int intel_i810_configure(void)
 
 	current_size = A_SIZE_FIX(agp_bridge->current_size);
 
-	pci_read_config_dword(intel_i810_private.i810_dev, I810_MMADDR, &temp);
-	temp &= 0xfff80000;
-
-	intel_i810_private.registers = ioremap(temp, 128 * 4096);
 	if (!intel_i810_private.registers) {
-		printk(KERN_ERR PFX "Unable to remap memory.\n");
-		return -ENOMEM;
+		pci_read_config_dword(intel_i810_private.i810_dev, I810_MMADDR, &temp);
+		temp &= 0xfff80000;
+
+		intel_i810_private.registers = ioremap(temp, 128 * 4096);
+		if (!intel_i810_private.registers) {
+			printk(KERN_ERR PFX "Unable to remap memory.\n");
+			return -ENOMEM;
+		}
 	}
 
 	if ((readl(intel_i810_private.registers+I810_DRAM_CTL)
-- 
http://www.codemonkey.org.uk
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