On 9/6/2015 7:16 PM, Frank Rowand wrote:
> On 9/6/2015 1:46 PM, Rob Herring wrote:
>> On Fri, Sep 4, 2015 at 8:14 PM, Frank Rowand <frowand.list@xxxxxxxxx> wrote:
>>> On 9/4/2015 12:12 PM, David Daney wrote:
>>>> From: David Daney <david.daney@xxxxxxxxxx>
>>>>
>>>> It is perfectly legitimate for a PCI device to have an
>>>> PCI_INTERRUPT_PIN value of zero. This happens if the device doesn't
>>>> use interrupts, or on PCIe devices, where only MSI/MSI-X are
>>>> supported.
>>>>
>>>> Silence the annoying "of_irq_parse_pci() failed with rc=-19" error
>>>> messages by making them conditional on !-ENODEV (which can only be
>>>> produced in the PCI_INTERRUPT_PIN == 0 case).
>>>>
>>>> Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
>>>> ---
>>>> drivers/of/of_pci_irq.c | 4 +++-
>>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/of/of_pci_irq.c b/drivers/of/of_pci_irq.c
>>>> index 1710d9d..33d242a 100644
>>>> --- a/drivers/of/of_pci_irq.c
>>>> +++ b/drivers/of/of_pci_irq.c
>>>> @@ -106,7 +106,9 @@ int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
>>>>
>>>> ret = of_irq_parse_pci(dev, &oirq);
>>>> if (ret) {
>>>> - dev_err(&dev->dev, "of_irq_parse_pci() failed with rc=%d\n", ret);
>>>> + if (ret != -ENODEV)
>>>> + dev_err(&dev->dev,
>>>> + "of_irq_parse_pci() failed with rc=%d\n", ret);
>>>> return 0; /* Proper return code 0 == NO_IRQ */
>>>> }
>>>>
>>>>
>>>
>>> It is not safe to assume that the functions that of_irq_parse_pci() calls
>>> will never be modified to return -ENODEV, thus resulting in of_irq_parse_pci()
>>> returning -ENODEV for a reason other than PCI_INTERRUPT_PIN == 0.
>>
>> Yes, but we're talking about a print statement.
>>
>>>
>>> A more robust solution would be something like:
>
> < snip my bad solution >
>
>>> I'm not sure I like my solution, there might be a better way.
>>
>> I don't like it. That's way too complex for just silencing an
>> erroneous error message.
>>
>> Perhaps just move the error message into of_irq_parse_pci and then you
>> can control the print more easily. Or just change to dev_dbg would be
>> okay by me.
>
> I knew I was making it way too hard. Yes, just move the error message
> to of_irq_parse_pci(), where the "/* No pin, exit */" test occurs.
And this time I replied too quickly, not really thinking through my comment.
There are several error return points in of_irq_parse_pci(), so moving the
error message into of_irq_parse_pci() is not the answer.
>>> I also noticed another bug while looking at of_irq_parse_pci(). It returns
>>> the non-zero return value from pci_read_config_byte(). But that value is
>>> one of the PCI function error values from include/linux/pci.h, such as:
>>>
>>> #define PCIBIOS_BAD_REGISTER_NUMBER 0x87
>>>
>>> instead of a negative errno.
>>
>> I was puzzled by why this is not standard error codes a while back. My
>> best guess is that that there is some legacy here. Changing error
>> values on widely used functions is impossible to audit. NO_IRQ being 0
>> or -1 is one such case.
>>
>> Rob
>>
>
>
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