Re: [PATCH 2/2] PCI: Warn if power_state != PCI_D0 when write MSI message

[Yijing Wang <wangyijing@huawei.com>]

>> @@ -291,6 +291,8 @@ void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
>>  {
>>         if (entry->dev->current_state != PCI_D0) {
>>                 /* Don't touch the hardware now */
>> +               dev_warn(&entry->dev->dev,
>> +                       "current_state != PCI_D0, ignore writing MSI message!\n");
> 
> Is there a real problem here?  If there is a real problem, a printk
> doesn't help fix it.  If there's no problem, I don't see the point of
> this printk.
> 
> I would expect that if the device is not in D0, we should remember the
> hardware updates that need to be made, and if the device returns to
> D0, we should apply the updates then.  If that's the case this is not
> an error and we shouldn't warn about it.

My colleagues found some msi irqs can not work normally in their driver which works
normally in SLES11 SP1(2.6.32 kernel). I review their code and found that they forget to
call pci_enable_device(), so their device always in PCI_UNKNOWN state despite the really PCI Power
State in PM register is PCI_D0 state. In this case, users call pci_enable_msi() always return success,
but actually, nothing was wrote to the MSI registers.

So I think we should warn here, if someone use pci_enable_msi(), but their devices are not in PCI_D0.

Thanks!
Yijing.

> 
>>         } else if (entry->msi_attrib.is_msix) {
>>                 void __iomem *base;
>>                 base = entry->mask_base +
>> --
>> 1.7.1
>>
>>
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> 
> 


-- 
Thanks!
Yijing