[PATCH RFC 1/2] PCI: Restore original PCI_COMMAND value in pcim_release

[Heiner Kallweit <hkallweit1@gmail.com>]

Instead of the complex handling of INTX and MWI in PCi devres, let's
simply restore the original vale of PCI_COMMAND in pcim_release().

Only side effect I've seen so far is that the "enabling device" info
message is printed each time a driver is re-probed after a EPROBE_DEFER.
I propose to silence this message by changing it to debug level.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/pci/devres.c | 8 ++------
 drivers/pci/probe.c  | 3 +++
 include/linux/pci.h  | 1 +
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index 2c562b9ea..7766f4df4 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -172,14 +172,10 @@ static void pcim_release(struct device *gendev, void *res)
 		if (this->region_mask & (1 << i))
 			pci_release_region(dev, i);
 
-	if (this->mwi)
-		pci_clear_mwi(dev);
-
-	if (this->restore_intx)
-		pci_intx(dev, this->orig_intx);
-
 	if (this->enabled && !this->pinned)
 		pci_disable_device(dev);
+
+	pci_write_config_word(dev, PCI_COMMAND, dev->pci_command);
 }
 
 /*
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1325fbae2..60052c979 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2558,6 +2558,9 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 
 	pci_init_capabilities(dev);
 
+	/* Store original register value */
+	pci_read_config_word(dev, PCI_COMMAND, &dev->pci_command);
+
 	/*
 	 * Add the device to our list of discovered devices
 	 * and the bus list for fixup functions, etc.
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 16493426a..92c3c99c9 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -352,6 +352,7 @@ struct pci_dev {
 	u8		rom_base_reg;	/* Config register controlling ROM */
 	u8		pin;		/* Interrupt pin this device uses */
 	u16		pcie_flags_reg;	/* Cached PCIe Capabilities Register */
+	u16		pci_command;	/* Restore original value in pci_disable_device */
 	unsigned long	*dma_alias_mask;/* Mask of enabled devfn aliases */
 
 	struct pci_driver *driver;	/* Driver bound to this device */
-- 
2.44.0