linux-kernel - [PATCH v4 0/9] PCI/MSI: Introduce pci_auto_enable

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Date:	Mon, 16 Dec 2013 09:34:53 +0100
From:	Alexander Gordeev <agordeev@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Alexander Gordeev <agordeev@...hat.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Michael Ellerman <michael@...erman.id.au>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Tejun Heo <tj@...nel.org>,
	Ben Hutchings <bhutchings@...arflare.com>,
	David Laight <David.Laight@...LAB.COM>,
	Mark Lord <kernel@...rt.ca>, "H. Peter Anvin" <hpa@...or.com>,
	linux-pci@...r.kernel.org
Subject: [PATCH v4 0/9] PCI/MSI: Introduce pci_auto_enable_msi*() family helpers

This series is against "next" branch in Bjorn's repo:
git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git

Changes from v3 to v4:
  - pcim_enable_msi* functions renamed to pci_auto_enable_msi* ones
  - PowerPC patches dropped
  - pci_get_msi_cap()     renamed to pci_get_msix_vec_count() and
    pci_msix_table_size() renamed to pci_get_msix_vec_count()

Changes from v2 to v3:
  - new public interfaces commented in drivers/pci/msi.c;
  - patch "Make quota traversing and requesting race-safe" explained;
  - pci_enable_msi/msix() 'nvec' arg type changed from 'unsigned int' to 'int';
  - pcim_enable_msi*() arg 'nvec' renamed to 'maxvec' when upper limit passed;
  - pcim_enable_msi*(..., maxvec, minvec) arg order swapped to minvec, maxvec;
  - "PCI: Fail MSI/MSI-X initialization if device is not in PCI_D0" commit
    869a161 and "PCI/MSI: Factor out pci_get_msi_cap() interface" patch
    conflicts resolved;

Currently many device drivers need contiguously call functions
pci_enable_msix() for MSI-X or pci_enable_msi_block() for MSI
in a loop until success or failure. This update generalizes
this usage pattern and introduces pci_auto_enable_msi*() family
helpers.

As result, device drivers do not have to deal with tri-state
return values from pci_enable_msix() and pci_enable_msi_block()
functions directly and expected to have more clearer and straight
code.

So i.e. the request loop described in the documentation...

	int foo_driver_enable_msix(struct foo_adapter *adapter,
				   int nvec)
	{
		while (nvec >= FOO_DRIVER_MINIMUM_NVEC) {
			rc = pci_enable_msix(adapter->pdev,
					     adapter->msix_entries,
					     nvec);
			if (rc > 0)
				nvec = rc;
			else
				return rc;
		}

		return -ENOSPC;
	}

...would turn into a single helper call....

	rc = pci_auto_enable_msix_range(adapter->pdev,
					adapter->msix_entries,
					FOO_DRIVER_MINIMUM_NVEC,
					nvec);

Device drivers with more specific requirements (i.e. a number of
MSI-Xs which is a multiple of a certain number within a specified
range) would still need to implement the loop using the two old
functions.

The tree could be found in "pci-next-msi-v4" branch in repo:
https://github.com/a-gordeev/linux.git


Alexander Gordeev (9):
  PCI/MSI/s390: Fix single MSI only check
  PCI/MSI/s390: Remove superfluous check of MSI type
  PCI/MSI: Fix return value when populate_msi_sysfs() failed
  PCI/MSI: Return -ENOSYS for unimplemented interfaces, not -1
  PCI/MSI: Make pci_enable_msi/msix() 'nvec' argument type as int
  PCI/MSI: Factor out pci_get_msi_vec_count() interface
  PCI/MSI: Get rid of pci_enable_msi_block_auto() interface
  PCI/MSI: Introduce pci_get_msix_vec_count() interface
  PCI/MSI: Introduce pci_auto_enable_msi*() family helpers

 Documentation/PCI/MSI-HOWTO.txt |  175 +++++++++++++++++++++++++++++++++------
 arch/s390/pci/pci.c             |    4 +-
 drivers/ata/ahci.c              |   56 ++++++++-----
 drivers/pci/msi.c               |  163 +++++++++++++++++++++++++++---------
 drivers/pci/pcie/portdrv_core.c |    7 +-
 include/linux/pci.h             |   78 +++++++++++++++---
 6 files changed, 380 insertions(+), 103 deletions(-)

-- 
1.7.7.6

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