Hi Bjorn
Many thanks for your review.
在 2018/3/13 8:18, Bjorn Helgaas 写道:
[+cc Rafael, linux-acpi]
On Sat, Mar 10, 2018 at 10:58:12AM +0800, Dongdong Liu wrote:
The init value of dev->irq is from PCI_INTERRUPT_LINE register.The default
value of dev->irq usually is 255 before calling acpi_pci_irq_enable().
This will cause a problem When the platform does not support INTx well.
For example, we do not config _PRT on our HIP07 platform, we met irq 255
confilict.
s/confilict/conflict/
arm64 calls acpi_pci_irq_enable() in the probe() path instead of in
the pci_enable_device() path. I can't remember the reason, and
unfortunately we didn't add a comment explaining why arm64 has to be
different.
PCI_INTERRUPT_LINE is used only by software and has no effect on the
hardware. If it contains 255 when Linux boots, that means firmware
must have set it to that value.
We need some comment here about why we should always ignore what
firmware put there on arm64. It needs to explain why this is
different on arm64 than it is on x86 and ia64. The changelog above
basically says "we need this to make it work", but that's not very
informative or convincing.
PCI 3.0, Section 6.2.4,
Interrupt Line
Values in this register are system architecture specific.
For x86 based PCs, the values in this register correspond to IRQ
numbers (0-15) of the standard dual 8259 configuration. The value
255 is defined as meaning "unknown" or "no connection" to the interrupt
controller. Values between 15 and 254 are reserved.
It seems the value of Interrupt Line is not defined on ARM64.
X86 has converted the irq 255 to IRQ_NOTCONNECTED in acpi_pci_irq_valid(),
but ARM64 does not, so it will not have irq 255 conflict on X86, but
ARM64 may have the issue if the BIOS does not provide _PRT.
static inline bool acpi_pci_irq_valid(struct pci_dev *dev, u8 pin)
{
#ifdef CONFIG_X86
/*
* On x86 irq line 0xff means "unknown" or "no connection"
* (PCI 3.0, Section 6.2.4, footnote on page 223).
*/
if (dev->irq == 0xff) {
dev->irq = IRQ_NOTCONNECTED;
dev_warn(&dev->dev, "PCI INT %c: not connected\n",
pin_name(pin));
return false;
}
#endif
return true;
}
It sounds like you're saying HIP07 doesn't provide _PRT? Per the PCI
Firmware Spec, r3.0, sec 4.4, _PRT is required under all PCI host
bridges. So I think you're saying HIP07 doesn't comply with the spec,
Yes, It does not support to use _PRT on the Hip07.
but the workaround here applies to *all* arm64 platforms. That
doesn't seem right.
Yes, it seems the Interrupt Line register is useless on ARM64
from current code.
On x86, I think if the _PRT doesn't tell us where an interrupt pin is
routed, we fall back to looking at PCI_INTERRUPT_LINE. But here
you seem to be saying "there's no _PRT" *and* "there's no useful
information in PCI_INTERRUPT_LINE".
Maybe I'm not understanding what you're saying.
The irq 255 conflict issue can be resolved by BIOS to set PCI device's
Interrupt Line register from 255(0xff) to 0.
or modify the code as below if ARM64 has the same meaning with X86 about
Interrupt Line register.
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -390,7 +390,7 @@ static inline int acpi_isa_register_gsi(struct pci_dev *dev)
static inline bool acpi_pci_irq_valid(struct pci_dev *dev, u8 pin)
{
-#ifdef CONFIG_X86
+#if defined(CONFIG_X86) || defined(CONFIG_ARM64)
/*
* On x86 irq line 0xff means "unknown" or "no connection"
* (PCI 3.0, Section 6.2.4, footnote on page 223).
Thanks,
Dongdong
The error message is as below.
snd_hda_intel 000d:33:00.1: PCI INT B: no GSI
snd_hda_intel 000d:33:00.1: enabling device (0000 -> 0002)
snd_hda_intel 000d:33:00.1: Force to snoop mode by module option
snd_hda_intel 000d:33:00.1: Device has broken 64-bit MSI but arch tried to
assign one above 4G
genirq: Flags mismatch irq 255. 00000001 (enahisic2i0-tx1) vs. 00000081
(snd_hda_intel:card0)
hns-nic HISI00C2:00 enahisic2i0: request irq(255) fail
enahisic2i0-tx1: this device is a platform device.
snd_hda_intel:card0: this device is a PCI device.
Signed-off-by: Dongdong Liu <liudongdong3@xxxxxxxxxx>
---
arch/arm64/kernel/pci.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 0e2ea1c..6a77bef 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -28,8 +28,11 @@
*/
int pcibios_alloc_irq(struct pci_dev *dev)
{
- if (!acpi_disabled)
+ if (!acpi_disabled) {
+ dev->irq = 0;
acpi_pci_irq_enable(dev);
+ }
+
return 0;
}
--
1.9.1
.
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