linux-toradex.git/Documentation/PCI/MSI-HOWTO.txt, branch v4.9.100

PCI: Use positive flags in pci_alloc_irq_vectors()

2016-08-16T19:07:30+00:00

Instead of passing negative flags like PCI_IRQ_NOMSI to prevent use of
certain interrupt types, pass positive flags like PCI_IRQ_LEGACY,
PCI_IRQ_MSI, etc., to specify the acceptable interrupt types.

This is based on a number of pending driver conversions that just happend
to be a whole more obvious to read this way, and given that we have no
users in the tree yet it can still easily be done.

I've also added a PCI_IRQ_ALL_TYPES catchall to keep the case of accepting
all interrupt types very simple.

[bhelgaas: changelog, fix PCI_IRQ_AFFINITY doc typo, remove mention of
PCI_IRQ_NOLEGACY]
Signed-off-by: Christoph Hellwig 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Alexander Gordeev

PCI: Spread interrupt vectors in pci_alloc_irq_vectors()

2016-07-21T20:57:03+00:00

Set the affinity_mask in the PCI device before allocating vectors so that
the affinity can be propagated through the MSI descriptor structures to the
core IRQ code.  To facilitate this, new __pci_enable_msi_range() and
__pci_enable_msix_range() helpers are factored out of their not prefixed
variants which assigning the new IRQ affinity mask in the PCI device so
that the low-level interrupt code can perform the interrupt affinity
assignment and do node-local allocations.

A new PCI_IRQ_NOAFFINITY flag is added to pci_alloc_irq_vectors() so that
this function can also be used by drivers that don't wish to use the
automatic affinity assignment.

[bhelgaas: omit "else" after "return" consistently]
Signed-off-by: Christoph Hellwig 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Alexander Gordeev

PCI: Provide sensible IRQ vector alloc/free routines

2016-07-21T20:50:07+00:00

Add a function to allocate and free a range of interrupt vectors, using
MSI-X, MSI or legacy vectors (in that order) based on the capabilities of
the underlying device and PCIe complex.

Additionally a new helper is provided to get the Linux IRQ number for given
device-relative vector so that the drivers don't need to allocate their own
arrays to keep track of the vectors for the multi vector MSI-X case.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Alexander Gordeev

doc:pci: Fix typo in Documentation/PCI

2015-03-20T13:41:56+00:00

This patch fix spelling typo in Documentation/PCI.

Signed-off-by: Masanari Iida 
Signed-off-by: Jonathan Corbet

MSI-HOWTO.txt: remove reference on IRQF_DISABLED

2015-03-20T13:41:55+00:00

The IRQF_DISABLED is a NOOP and scheduled to be removed.  According to Ingo
Molnar in commit e58aa3d2d0cc01ad8d6f7f640a0670433f794922 (genirq: Run irq
handlers with interrupts disabled), running IRQ handlers with interrupts
enabled can cause stack overflows when the interrupt line of the issuing
device is still active.

This patch removes IRQF_DISABLED from this documentation.  It was
mentioned to be a solution to avoid deadlocks when a device uses
multiple interrupts.  As the flag is a NOOP this solution does not work
anymore.

Signed-off-by: Valentin Rothberg 
Signed-off-by: Jonathan Corbet

doc: replace "practise" with "practice" in Documentation

2014-06-19T13:28:56+00:00

To keep the Documentation consistent either
"practise" or "practice" should be used.

Since there are 3 lines with "practise"

  ~/linux/Documentation$ grep -r practise * | wc -l
  3

and 108 lines with "practice"

  ~/linux/Documentation$ grep -r practice * | wc -l
  108

this patch converts "practise" to "practice".

Signed-off-by: Jeremiah Mahler 
Signed-off-by: Jiri Kosina

PCI/MSI: Add pci_enable_msi_exact() and pci_enable_msix_exact()

2014-02-13T17:48:02+00:00

The new functions are special cases for pci_enable_msi_range() and
pci_enable_msix_range() when a particular number of MSI or MSI-X
is needed.

By contrast with pci_enable_msi_range() and pci_enable_msix_range()
functions, pci_enable_msi_exact() and pci_enable_msix_exact()
return zero in case of success, which indicates MSI or MSI-X
interrupts have been successfully allocated.

Signed-off-by: Alexander Gordeev 
Signed-off-by: Bjorn Helgaas

PCI/MSI: Fix cut-and-paste errors in documentation

2014-02-13T17:47:56+00:00

Function pci_enable_msi_range() is used in examples where
pci_enable_msix_range() should have been used instead.

Reported-by: Bjorn Helgaas 
Signed-off-by: Alexander Gordeev 
Signed-off-by: Bjorn Helgaas

PCI/MSI: Add pci_enable_msi() documentation back

2014-02-13T17:47:51+00:00

We deprecated pci_enable_msi() in 302a2523c277 ("PCI/MSI: Add
pci_enable_msi_range() and pci_enable_msix_range()").

But we changed our minds after noticing that:

  - pci_enable_msi() doesn't have confusing return values like
    pci_enable_msi_block() and pci_enable_msix() did, and

  - pci_enable_msi() has a hundred or so callers that we don't want to
    change.

This adds back the pci_enable_msi() documentation.

[bhelgaas: changelog]
Signed-off-by: Alexander Gordeev 
Signed-off-by: Bjorn Helgaas

PCI/MSI: Add pci_enable_msi_range() and pci_enable_msix_range()

2014-01-04T00:17:55+00:00

This adds pci_enable_msi_range(), which supersedes the pci_enable_msi()
and pci_enable_msi_block() MSI interfaces.

It also adds pci_enable_msix_range(), which supersedes the
pci_enable_msix() MSI-X interface.

The old interfaces have three categories of return values:

    negative: failure; caller should not retry
    positive: failure; value indicates number of interrupts that *could*
	have been allocated, and caller may retry with a smaller request
    zero: success; at least as many interrupts allocated as requested

It is error-prone to handle these three cases correctly in drivers.

The new functions return either a negative error code or a number of
successfully allocated MSI/MSI-X interrupts, which is expected to lead to
clearer device driver code.

pci_enable_msi(), pci_enable_msi_block() and pci_enable_msix() still exist
unchanged, but are deprecated and may be removed after callers are updated.

[bhelgaas: tweak changelog]
Suggested-by: Ben Hutchings 
Signed-off-by: Alexander Gordeev 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Tejun Heo