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SubjectRe: [Bug] PCI: Enable INTx if BIOS left them disabled - triggers during rescan
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On Fri, Mar 7, 2014 at 8:45 AM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>
> I opened a bugzilla report at https://bugzilla.kernel.org/show_bug.cgi?id=71691
>
> It seems like clearing DisINTx has some effect on MSI. I don't see
> anything in the spec that would suggest this (I'm looking at the PCIe
> r3.0 spec, sec 7.5.1.1).
>
> Can somebody point out a connection between DisINTx and MSI? If not,
> maybe we'll need some sort of quirk to deal with this.

I had different impression: if you disable INTx in some chipset, MSI will not
work anymore.

so we have

static void pci_intx_for_msi(struct pci_dev *dev, int enable)
{
if (!(dev->dev_flags & PCI_DEV_FLAGS_MSI_INTX_DISABLE_BUG))
pci_intx(dev, enable);
}

and have quirks for ati and broadcom chip to set that FLAG.

regarding the regression: i would suggest move out
do_pci_enable_intx() from re-enable path.

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5a24cb3..92718c9 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1190,11 +1190,22 @@ int __weak pcibios_enable_device(struct
pci_dev *dev, int bars)
return pci_enable_resources(dev, bars);
}

+static void do_pci_enable_intx(struct pci_dev *dev)
+{
+ u8 pin;
+ pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
+ if (pin) {
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ if (cmd & PCI_COMMAND_INTX_DISABLE)
+ pci_write_config_word(dev, PCI_COMMAND,
+ cmd & ~PCI_COMMAND_INTX_DISABLE);
+ }
+}
+
static int do_pci_enable_device(struct pci_dev *dev, int bars)
{
int err;
u16 cmd;
- u8 pin;

err = pci_set_power_state(dev, PCI_D0);
if (err < 0 && err != -EIO)
@@ -1204,14 +1215,6 @@ static int do_pci_enable_device(struct pci_dev
*dev, int bars)
return err;
pci_fixup_device(pci_fixup_enable, dev);

- pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
- if (pin) {
- pci_read_config_word(dev, PCI_COMMAND, &cmd);
- if (cmd & PCI_COMMAND_INTX_DISABLE)
- pci_write_config_word(dev, PCI_COMMAND,
- cmd & ~PCI_COMMAND_INTX_DISABLE);
- }
-
return 0;
}

@@ -1287,6 +1290,8 @@ static int pci_enable_device_flags(struct
pci_dev *dev, unsigned long flags)
err = do_pci_enable_device(dev, bars);
if (err < 0)
atomic_dec(&dev->enable_cnt);
+ else
+ do_pci_enable_intx(dev);
return err;
}
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5a24cb3..92718c9 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1190,11 +1190,22 @@ int __weak pcibios_enable_device(struct pci_dev *dev, int bars)
return pci_enable_resources(dev, bars);
}

+static void do_pci_enable_intx(struct pci_dev *dev)
+{
+ u8 pin;
+ pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
+ if (pin) {
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ if (cmd & PCI_COMMAND_INTX_DISABLE)
+ pci_write_config_word(dev, PCI_COMMAND,
+ cmd & ~PCI_COMMAND_INTX_DISABLE);
+ }
+}
+
static int do_pci_enable_device(struct pci_dev *dev, int bars)
{
int err;
u16 cmd;
- u8 pin;

err = pci_set_power_state(dev, PCI_D0);
if (err < 0 && err != -EIO)
@@ -1204,14 +1215,6 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
return err;
pci_fixup_device(pci_fixup_enable, dev);

- pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
- if (pin) {
- pci_read_config_word(dev, PCI_COMMAND, &cmd);
- if (cmd & PCI_COMMAND_INTX_DISABLE)
- pci_write_config_word(dev, PCI_COMMAND,
- cmd & ~PCI_COMMAND_INTX_DISABLE);
- }
-
return 0;
}

@@ -1287,6 +1290,8 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
err = do_pci_enable_device(dev, bars);
if (err < 0)
atomic_dec(&dev->enable_cnt);
+ else
+ do_pci_enable_intx(dev);
return err;
}
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