[3.16.y-ckt stable] Patch "gpu/radeon: Set flag to indicate broken 64-bit MSI" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    gpu/radeon: Set flag to indicate broken 64-bit MSI

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt3.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From d6d71e6ad66bc07bd27da962d5a66a8cca411d04 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Date: Fri, 3 Oct 2014 15:18:59 +1000
Subject: gpu/radeon: Set flag to indicate broken 64-bit MSI

commit 91ed6fd2c383bb8f02d66e98b4a4d2f7207249dc upstream.

Some radeon ASICs don't support all 64 address bits of MSIs despite
advertising support for 64-bit MSIs in their configuration space.

This breaks on systems such as IBM POWER7/8, where 64-bit MSIs can
be assigned with some of the high address bits set.

This makes use of the newly introduced "no_64bit_msi" flag in structure
pci_dev to allow the MSI allocation code to fallback to 32-bit MSIs
on those adapters.

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/radeon/radeon_irq_kms.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c
index 16807afab362..c74f12d125f7 100644
--- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
@@ -202,6 +202,16 @@ static bool radeon_msi_ok(struct radeon_device *rdev)
 	if (rdev->flags & RADEON_IS_AGP)
 		return false;

+	/*
+	 * Older chips have a HW limitation, they can only generate 40 bits
+	 * of address for "64-bit" MSIs which breaks on some platforms, notably
+	 * IBM POWER servers, so we limit them
+	 */
+	if (rdev->family < CHIP_BONAIRE) {
+		dev_info(rdev->dev, "radeon: MSI limited to 32-bit\n");
+		rdev->pdev->no_64bit_msi = 1;
+	}
+
 	/* force MSI on */
 	if (radeon_msi == 1)
 		return true;