Patch "x86/pci/intel_mid_pci: Work around for IRQ0 assignment" has been added to the 4.2-stable tree

This is a note to let you know that I've just added the patch titled

x86/pci/intel_mid_pci: Work around for IRQ0 assignment

to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-pci-intel_mid_pci-work-around-for-irq0-assignment.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Andy Shevchenko <[email protected]>
Date: Wed, 29 Jul 2015 12:16:47 +0300
Subject: x86/pci/intel_mid_pci: Work around for IRQ0 assignment

From: Andy Shevchenko <[email protected]>

commit 39d9b77b8debb4746e189aa5b61ae6e81ec5eab8 upstream.

On Intel Tangier the MMC host controller is wired up to irq 0. But several other devices have irq 0 associated as well due to a bogus PCI configuration.

The first initialized driver will acquire irq 0 and make it unavailable for other devices. If the sdhci driver is not the first one it will fail to acquire the interrupt and therefor be non functional.

Add a quirk to the pci irq enable function which denies irq 0 to anything else than the MMC host controller driver on Tangier platforms.

---
 arch/x86/pci/intel_mid_pci.c |   24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

@@ -35,6 +35,9 @@
 
 #define PCIE_CAP_OFFSET	0x100
 
+/* Quirks for the listed devices */
+#define PCI_DEVICE_ID_INTEL_MRFL_MMC	0x1190
+
 /* Fixed BAR fields */
 #define PCIE_VNDR_CAP_ID_FIXED_BAR 0x00	/* Fixed BAR (TBD) */
 #define PCI_FIXED_BAR_0_SIZE	0x04

@@ -214,10 +217,27 @@ static int intel_mid_pci_irq_enable(stru
 	if (dev->irq_managed && dev->irq > 0)
 		return 0;
 
-	if (intel_mid_identify_cpu() == INTEL_MID_CPU_CHIP_TANGIER)
+	switch (intel_mid_identify_cpu()) {
+	case INTEL_MID_CPU_CHIP_TANGIER:
 		polarity = 0; /* active high */
-	else
+
+		/* Special treatment for IRQ0 */
+		if (dev->irq == 0) {
+			/*
+			 * TNG has IRQ0 assigned to eMMC controller. But there
+			 * are also other devices with bogus PCI configuration
+			 * that have IRQ0 assigned. This check ensures that
+			 * eMMC gets it.
+			 */
+			if (dev->device != PCI_DEVICE_ID_INTEL_MRFL_MMC)
+				return -EBUSY;
+		}
+		break;
+	default:
 		polarity = 1; /* active low */
+		break;
+	}
+
 	ioapic_set_alloc_attr(&info, dev_to_node(&dev->dev), 1, polarity);
 
 	/*

Patches currently in stable-queue which might be from [email protected] are

queue-4.2/dmaengine-dw-properly-read-dwc_params-register.patch queue-4.2/x86-pci-intel_mid_pci-work-around-for-irq0-assignment.patch