On Mon, Jun 13, 2016 at 11:40:05AM +0100, Lorenzo Pieralisi wrote:
On Fri, Jun 10, 2016 at 06:36:12PM -0500, Bjorn Helgaas wrote:
On Fri, Jun 10, 2016 at 09:55:17PM +0200, Tomasz Nowicki wrote:
To enable PCI legacy IRQs on platforms booting with ACPI, arch code should include ACPI specific callbacks that parse and set-up the device IRQ number, equivalent to the DT boot path. Owing to the current ACPI core scan handlers implementation, ACPI PCI legacy IRQs bindings cannot be parsed at device add time, since that would trigger ACPI scan handlers ordering issues depending on how the ACPI tables are defined.
Uh, OK :) I can't figure out exactly what the problem is here -- I don't know where to look if I wanted to fix the scan handler ordering issues, and I don't know how I could tell if it would ever be safe to move this from driver probe-time back to device add-time.
Right, the commit log could have been more informative.
pcibios_add_device() was added in:
commit d1e6dc91b532 ("arm64: Add architectural support for PCI")
whose commit log does not specify why legacy IRQ parsing should be done at pcibios_add_device() either, so honestly we had to do with the information we have at hand.
Because at that time (September 2014) there was no pcibios_alloc_irq() (added June 2015 by commit 890e4847587fcf) and after that nobody bothered to update the arm64 code to make use of the new API.
Best regards, Liviu
I also notice that x86 and ia64 call acpi_pci_irq_enable() even later, when the driver *enables* the device. Is there a reason you didn't do it at the same time as x86 and ia64? This is another of those pcibios hooks that really don't do anything arch-specific, so I can imagine refactoring this somehow, someday.
Yes, with [1], that was the goal, that stopped because [1] does not work on x86.
Only DT platform(s) affected by this change are all platforms relying on drivers/pci/host/pci-xgene.c (others rely on pci_fixup_irqs() that should be removed too), if on those platforms probing IRQs at device enable time works ok I can update this patch (it can be done through [1] once we figure out what to do with it on x86) and move the IRQ set-up at pcibios_enable_device() time.
@Duc: any feedback on this ?
Thanks, Lorenzo
[1] http://www.spinics.net/lists/linux-pci/msg45950.html
Did we have this conversation before? It seems vaguely familiar, so I apologize if you already explained this once.
To solve this problem and consolidate FW PCI legacy IRQs parsing in one single pcibios callback (pending final removal), this patch moves DT PCI IRQ parsing to the pcibios_alloc_irq() callback (called by PCI core code at device probe time) and adds ACPI PCI legacy IRQs parsing to the same callback too, so that FW PCI legacy IRQs parsing is confined in one single arch callback that can be easily removed when code parsing PCI legacy IRQs is consolidated and moved to core PCI code.
Signed-off-by: Tomasz Nowicki tn@semihalf.com Suggested-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com
arch/arm64/kernel/pci.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c index d5d3d26..b3b8a2c 100644 --- a/arch/arm64/kernel/pci.c +++ b/arch/arm64/kernel/pci.c @@ -51,11 +51,16 @@ int pcibios_enable_device(struct pci_dev *dev, int mask) } /*
- Try to assign the IRQ number from DT when adding a new device
*/
- Try to assign the IRQ number when probing a new device
-int pcibios_add_device(struct pci_dev *dev) +int pcibios_alloc_irq(struct pci_dev *dev) {
- dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
- if (acpi_disabled)
dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);+#ifdef CONFIG_ACPI
- else
return acpi_pci_irq_enable(dev);+#endif return 0; } -- 1.9.1