On Wed, Jun 15, 2016 at 10:09:38PM +0200, Arnd Bergmann wrote:

The PCI_MSI symbol is used inconsistently throughout the tree,
with some drivers using 'select' and others using 'depends on',
or using conditional selects. This keeps causing problems,
and the latest one is a result of ARCH_ALPINE using a 'select'
statement to enable its platform specific MSI driver but not
enabling MSI support first:

warning: (ARCH_ALPINE) selects ALPINE_MSI which has unmet direct dependencies (PCI && PCI_MSI)
drivers/irqchip/irq-alpine-msi.c:104:15: error: variable 'alpine_msix_domain_info' has initializer but incomplete type
 static struct msi_domain_info alpine_msix_domain_info = {
               ^~~~~~~~~~~~~~~
drivers/irqchip/irq-alpine-msi.c:105:2: error: unknown field 'flags' specified in initializer
  .flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
  ^
drivers/irqchip/irq-alpine-msi.c:105:11: error: 'MSI_FLAG_USE_DEF_DOM_OPS' undeclared here (not in a function)
  .flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
           ^~~~~~~~~~~~~~~~~~~~~~~~

There is little reason to enable PCI support for a platform that
uses MSI but then leaving MSI disabled at compile time.

I sent an earlier version that used 'select PCI_MSI' everywhere
in March, but that caused build regressions on x86.

This version instead selects PCI_MSI from irqchips that implement MSI,
and makes PCI host bridges that use MSI on ARM depend on PCI_MSI_IRQ_DOMAIN,
which in turn is now enabled by default on all three architectures that
support it, whenever MSI is enabled.

I think it makes most sense to merge this patch through the PCI tree,
as new PCI host drivers get added occasionally, and they all need to
be adapted for this change.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Marc Zyngier <redacted>
Acked-by: Marc Zyngier <redacted>

I applied this to pci/msi, minus the crypto change that looks unrelated: