[RFT PATCH v2 29/42] ARM: PCI: Remove pci_fixup_irqs() call for bios32 host controllers

[Bjorn Helgaas]

On Sat, Jul 01, 2017 at 03:06:30PM +0100, Lorenzo Pieralisi wrote:
> Hi Bjorn,
> 
> On Thu, Jun 08, 2017 at 03:13:29PM +0100, Lorenzo Pieralisi wrote:
> > Legacy PCI host controllers (ie host controllers that set-up the PCI bus
> > through the ARM pci_common_init() API) are currently relying on
> > pci_fixup_irqs() to assign legacy PCI irqs to devices. This is not ideal
> > in that pci_fixup_irqs() assign IRQs for all PCI devices present in a
> > given system some of which may well be enabled by the time
> > pci_fixup_irqs() is called (ie a system with multiple host controllers).
> > With the introduction of struct pci_host_bridge.(*map_irq) pointer it is
> > possible to assign IRQs for all devices originating from a PCI host
> > bridge at probe time; this is implemented through pci_assign_irq() that
> > relies on the struct pci_host_bridge.map_irq pointer to map IRQ for a
> > given device.
> > 
> > The benefits this brings are twofold:
> > 
> > - the IRQ for a device is assigned once at probe time
> > - the IRQ assignment works also for hotplugged devices
> > 
> > Remove pci_fixup_irqs() call from bios32 code and rely on
> > pci_assign_irq() to carry out the IRQ mapping at device probe
> > time.
> > 
> > The map_irq() and swizzle_irq() struct pci_host_bridge callbacks are
> > set-up in the struct pci_host_bridge created in the bios32
> > pcibios_init_hw() function and mach-* code paths (for PCI mach
> > implementations that require a specific struct hw_pci.(*scan) function
> > callback).
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> > Cc: Jason Cooper <jason at lakedaemon.net>
> > Cc: Bjorn Helgaas <bhelgaas at google.com>
> > Cc: Russell King <linux at armlinux.org.uk>
> > Cc: Andrew Lunn <andrew at lunn.ch>
> > ---
> >  arch/arm/kernel/bios32.c    |  4 ++--
> >  arch/arm/mach-dove/pcie.c   | 18 ++++++++++--------
> >  arch/arm/mach-iop13xx/pci.c |  2 ++
> >  arch/arm/mach-orion5x/pci.c | 28 +++++++++++++++-------------
> >  4 files changed, 29 insertions(+), 23 deletions(-)
> 
> As I mentioned to you, this patch is incomplete and needs an upgrade
> (ie I misread how Orion and the gazillions board file that go with
> it to map irqs - apologies but it is very hard to untangle).
> 
> I am inlining below an incremental patch to be folded in commit:
> 
> feaec00e757a ("ARM/PCI: Remove pci_fixup_irqs() call for bios32 host
> controllers")
> 
> in your pci/irq-fixups branch, or if you prefer I can send you the
> resulting squashed-in patch to replace this one, as you prefer.

Thanks, I folded this into pci/irq-fixups.  The resulting patch is
merely this:

commit 16508469c0f3198a63923aaec08efa1c63f5fbcc
Author: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Date:   Wed Jun 28 15:14:04 2017 -0500

    ARM/PCI: Remove pci_fixup_irqs() call for bios32 host controllers
    
    Legacy PCI host controllers (ie host controllers that set-up the PCI bus
    through the ARM pci_common_init() API) are currently relying on
    pci_fixup_irqs() to assign legacy PCI irqs to devices.  This is not ideal
    in that pci_fixup_irqs() assigns IRQs for all PCI devices present in a given
    system some of which may well be enabled by the time pci_fixup_irqs() is
    called (ie a system with multiple host controllers).  With the introduction
    of struct pci_host_bridge.(*map_irq) pointer it is possible to assign IRQs
    for all devices originating from a PCI host bridge at probe time; this is
    implemented through pci_assign_irq() that relies on the struct
    pci_host_bridge.map_irq pointer to map IRQ for a given device.
    
    The benefits this brings are twofold:
    
      - the IRQ for a device is assigned once at probe time
      - the IRQ assignment works also for hotplugged devices
    
    Remove pci_fixup_irqs() call from bios32 code and rely on pci_assign_irq()
    to carry out the IRQ mapping at device probe time.
    
    The map_irq() and swizzle_irq() struct pci_host_bridge callbacks are set-up
    in the struct pci_host_bridge created in the bios32 pcibios_init_hw()
    function and mach-* code paths (for PCI mach implementations that require a
    specific struct hw_pci.(*scan) function callback).
    
    Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
    [bhelgaas: folded in fixes from Lorenzo:
    http://lkml.kernel.org/r/20170701140629.GC8977@red-moon]
    Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
    Cc: Jason Cooper <jason at lakedaemon.net>
    Cc: Russell King <linux at armlinux.org.uk>
    Cc: Andrew Lunn <andrew at lunn.ch>

diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index 4c7621ac389c..56dc1a3a33b4 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -484,6 +484,9 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
 				break;
 			}
 
+			bridge->map_irq = pcibios_map_irq;
+			bridge->swizzle_irq = pcibios_swizzle;
+
 			if (hw->scan)
 				ret = hw->scan(nr, bridge);
 			else {
@@ -530,8 +533,6 @@ void pci_common_init_dev(struct device *parent, struct hw_pci *hw)
 	if (hw->postinit)
 		hw->postinit();
 
-	pci_fixup_irqs(pcibios_swizzle, pcibios_map_irq);
-
 	list_for_each_entry(sys, &head, node) {
 		struct pci_bus *bus = sys->bus;