PCI: export pci_restore_msi_state()

PCI error recovery usually involves the PCI adapter being reset. If the device is using MSI, the reset will cause the MSI state to be lost; the device driver needs to restore the MSI state.

The pci_restore_msi_state() routine is currently protected by CONFIG_PM; remove this, and also export the symbol, so that it can be used in a modle.

----
I am so sorry I wasn't able to send this 3 weeks ago, when I first wrote the patch. There was simply no functional hardware available to actually run this stuff :-(

Patches that use this, including those for tg3 and e1000e and ixgbe i.e. MSI-using drivers, are to follow "real soon now".

 drivers/pci/msi.c   |    3 +--
 drivers/pci/pci.h   |    6 ------
 include/linux/pci.h |    2 ++
 3 files changed, 3 insertions(+), 8 deletions(-)

Index: linux-2.6.23-rc8-mm1/drivers/pci/msi.c
===================================================================
@@ -224,7 +224,6 @@ static struct msi_desc* alloc_msi_entry(
 	return entry;
 }
 
-#ifdef CONFIG_PM
 static void __pci_restore_msi_state(struct pci_dev *dev)
 {
 	int pos;

@@ -282,7 +281,7 @@ void pci_restore_msi_state(struct pci_de
 	__pci_restore_msi_state(dev);
 	__pci_restore_msix_state(dev);
 }
-#endif	/* CONFIG_PM */
+EXPORT_SYMBOL_GPL(pci_restore_msi_state);
 
 /**
  * msi_capability_init - configure device's MSI capability structure

Index: linux-2.6.23-rc8-mm1/drivers/pci/pci.h
===================================================================
@@ -45,12 +45,6 @@ static inline void pci_no_msi(void) { }
 static inline void pci_msi_init_pci_dev(struct pci_dev *dev) { }
 #endif
 
-#if defined(CONFIG_PCI_MSI) && defined(CONFIG_PM)
-void pci_restore_msi_state(struct pci_dev *dev);
-#else
-static inline void pci_restore_msi_state(struct pci_dev *dev) {}
-#endif
-
 static inline int pci_no_d1d2(struct pci_dev *dev)
 {
 	unsigned int parent_dstates = 0;

Index: linux-2.6.23-rc8-mm1/include/linux/pci.h
===================================================================
@@ -665,6 +665,7 @@ static inline int pci_enable_msix(struct
 	struct msix_entry *entries, int nvec) {return -1;}
 static inline void pci_disable_msix(struct pci_dev *dev) {}
 static inline void msi_remove_pci_irq_vectors(struct pci_dev *dev) {}
+static inline void pci_restore_msi_state(struct pci_dev *dev) {}
 #else
 extern int pci_enable_msi(struct pci_dev *dev);
 extern void pci_disable_msi(struct pci_dev *dev);

@@ -672,6 +673,7 @@ extern int pci_enable_msix(struct pci_de
 	struct msix_entry *entries, int nvec);
 extern void pci_disable_msix(struct pci_dev *dev);
 extern void msi_remove_pci_irq_vectors(struct pci_dev *dev);
+extern void pci_restore_msi_state(struct pci_dev *dev);
 #endif
 
 #ifdef CONFIG_HT_IRQ

Hi,

The long time delay has managed to muddle notes & recollection of prior discussions. This patch should have had a

on it; its the same patch that was submitted a long time ago.

During the discussions of 21 Oct, it was proposed that there should be an arch hook for pci_restore_msi_state(), so that it would be treated at the same level as msi setup and teardown. I'd volunteered to write that patch.

When I sat down to do it, however, I realized that I did not actually *need* it. And so I wondered: why am I writing un-needed, but theoretically proper, code? So I punted, and I didn't. Does that make sense?

That's also why this patch is just a resubmission of the old patch. The original thread is here:

http://www.mail-archive.com/[email protected]/msg51296.html

--linas

And its an old patch, submitted long ago ... I've resubmitted, because it seems that its the best/most correct thing to do.

Yes, please. Note, however, I was never able to make the pci-e version of the e1000 work. It comes up, generates interrupts, and registeres are readable and writeable. But it behvaes as if the PHY is turned off -- no network traffic goes thorugh. (I tried turning PHY on explicitly; that didn't help). So there is still something wrong somewhere, probably in the e1000 deice driver. I'm guessing the pci-e to pci-x bridge chip on that card is not quite resetting the card completely.

There is no "save state", the msi state can't be saved. The MSI regs are write-only, and they are controlled by firmware. The restore_state function is the only one you need.

--linas