[tip:x86/pci] vgaarb: Add user selectability of the number of GPUS in a system

[tip-bot for Mike Travis <travis@sgi.com>]

Commit-ID:  5f95078a35e5857afa294a558c277196cf079668
Gitweb:     http://git.kernel.org/tip/5f95078a35e5857afa294a558c277196cf079668
Author:     Mike Travis <travis@sgi.com>
AuthorDate: Tue, 2 Feb 2010 14:38:16 -0800
Committer:  H. Peter Anvin <hpa@zytor.com>
CommitDate: Fri, 5 Feb 2010 14:05:41 -0800

vgaarb: Add user selectability of the number of GPUS in a system

Update the VGA Arbiter to allow the user to select the number of GPU's
supported in a system.

Signed-off-by: Mike Travis <travis@sgi.com>
LKML-Reference: <201002022238.o12McG1F018733@imap1.linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Robin Holt <holt@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 drivers/gpu/vga/Kconfig  |    8 ++++++++
 drivers/gpu/vga/vgaarb.c |    4 ++++
 2 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
index 790e675..cb1dcfe 100644
--- a/drivers/gpu/vga/Kconfig
+++ b/drivers/gpu/vga/Kconfig
@@ -8,3 +8,11 @@ config VGA_ARB
 	  are accessed at same time they need some kind of coordination. Please
 	  see Documentation/vgaarbiter.txt for more details. Select this to
 	  enable VGA arbiter.
+
+config VGA_ARB_MAX_GPUS
+	int "Maximum number of GPUs"
+	default 64
+	depends on VGA_ARB
+	help
+	  Reserves space in the kernel to maintain resource locking for
+	  multiple GPUS.  The overhead for each GPU is very small.
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index ba7fa9e..541fdfd 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -688,7 +688,11 @@ EXPORT_SYMBOL(vga_client_register);
  * the arbiter.
  */
 
+#ifdef CONFIG_VGA_ARB_MAX_GPUS
+#define MAX_USER_CARDS         CONFIG_VGA_ARB_MAX_GPUS
+#else
 #define MAX_USER_CARDS         16
+#endif
 #define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
 
 /*