linux-kernel - [PATCH v2] Setting the IORESOURCE_ROM_SHADOW flag on a VGA card other than the primary prevents it from reading it's own rom. It will get the content of the shadowrom at C000 instead, which is of the primary VGA card and the driver of the secondary card will bail out.

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Date:	Fri, 31 Jan 2014 10:28:23 +0100
From:	Sander Eikelenboom <linux@...elenboom.it>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Tony Luck <tony.luck@...el.com>,
	Dave Airlie <airlied@...hat.com>,
	Eiichiro Oiwa <eiichiro.oiwa.nm@...achi.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Sander Eikelenboom <linux@...elenboom.it>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"linux-kernel @ vger . kernel . org" <linux-kernel@...r.kernel.org>,
	"linux-pci @ vger . kernel . org" <linux-pci@...r.kernel.org>,
	linux-ia64@...r.kernel.org
Subject: [PATCH v2] Setting the IORESOURCE_ROM_SHADOW flag on a VGA card other than the primary prevents it from reading it's own rom. It will get the content of the shadowrom at C000 instead, which is of the primary VGA card and the driver of the secondary card will bail out.

Fix this by checking if the arch code or vga-arbitration has already
determined the vga_default_device, if so only apply the fix to this
primary video device and let the comment reflect this.

Signed-off-by: Sander Eikelenboom <linux@...elenboom.it>
---
 arch/ia64/pci/fixup.c |   24 +++++++++++++-----------
 arch/x86/pci/fixup.c  |   18 ++++++++++--------
 2 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/arch/ia64/pci/fixup.c b/arch/ia64/pci/fixup.c
index 5dc969d..7762255 100644
--- a/arch/ia64/pci/fixup.c
+++ b/arch/ia64/pci/fixup.c
@@ -19,9 +19,10 @@
  * IORESOURCE_ROM_SHADOW is used to associate the boot video
  * card with this copy. On laptops this copy has to be used since
  * the main ROM may be compressed or combined with another image.
- * See pci_map_rom() for use of this flag. IORESOURCE_ROM_SHADOW
- * is marked here since the boot video device will be the only enabled
- * video device at this point.
+ * See pci_map_rom() for use of this flag. Before marking the device
+ * with IORESOURCE_ROM_SHADOW check if a vga_default_device is already set
+ * by either arch cde or vga-arbitration, if so only apply the fixup to this
+ * already determined primary video card.
  */
 
 static void pci_fixup_video(struct pci_dev *pdev)
@@ -35,9 +36,6 @@ static void pci_fixup_video(struct pci_dev *pdev)
 		return;
 	/* Maybe, this machine supports legacy memory map. */
 
-	if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
-		return;
-
 	/* Is VGA routed to us? */
 	bus = pdev->bus;
 	while (bus) {
@@ -60,10 +58,14 @@ static void pci_fixup_video(struct pci_dev *pdev)
 		}
 		bus = bus->parent;
 	}
-	pci_read_config_word(pdev, PCI_COMMAND, &config);
-	if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
-		pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
-		dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
+	if (!vga_default_device() || pdev == vga_default_device()) {
+		pci_read_config_word(pdev, PCI_COMMAND, &config);
+		if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
+			pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
+			dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
+			vga_set_default_device(pdev);
+		}
 	}
 }
-DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, pci_fixup_video);
+DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID,
+				PCI_CLASS_DISPLAY_VGA, 8, pci_fixup_video);
diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index b046e07..34528a7 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -314,9 +314,10 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_MCH_PC1,	pcie_r
  * IORESOURCE_ROM_SHADOW is used to associate the boot video
  * card with this copy. On laptops this copy has to be used since
  * the main ROM may be compressed or combined with another image.
- * See pci_map_rom() for use of this flag. IORESOURCE_ROM_SHADOW
- * is marked here since the boot video device will be the only enabled
- * video device at this point.
+ * See pci_map_rom() for use of this flag. Before marking the device
+ * with IORESOURCE_ROM_SHADOW check if a vga_default_device is already set
+ * by either arch cde or vga-arbitration, if so only apply the fixup to this
+ * already determined primary video card.
  */
 
 static void pci_fixup_video(struct pci_dev *pdev)
@@ -347,12 +348,13 @@ static void pci_fixup_video(struct pci_dev *pdev)
 		}
 		bus = bus->parent;
 	}
-	pci_read_config_word(pdev, PCI_COMMAND, &config);
-	if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
-		pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
-		dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
-		if (!vga_default_device())
+	if (!vga_default_device() || pdev == vga_default_device()) {
+		pci_read_config_word(pdev, PCI_COMMAND, &config);
+		if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
+			pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
+			dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
 			vga_set_default_device(pdev);
+		}
 	}
 }
 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID,
-- 
1.7.10.4

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