On Thu, 2013-11-14 at 11:23 +0800, mike wrote: > On 11/14/2013 03:20 AM, Alan Stern wrote: > > On Wed, 13 Nov 2013, Bjorn Helgaas wrote: > > > >> [+cc Rafael, linux-pm] > >> > >> On Wed, Nov 13, 2013 at 6:09 AM, mike<qiudayu@xxxxxxxxxxxxxxxxxx> wrote: > >>> Hi Huang Ying, > >>> > >>> I see you are the author of this patch, commit id is: > >>> 967577b062417b4e4b8e27b711220f4124f5153a > >>> > >>> I have a question while I try to understand this patch, > >>> So I would very grateful if you or others can give me some reply..... > >>> > >>> ............ > >>> - rc = ddi->drv->probe(ddi->dev, ddi->id); > >>> + pm_runtime_get_sync(dev); > >>> + pci_dev->driver = pci_drv; > >>> ^^^^^^^^^^^^^^^^^^^^^^^^^^ > >>> I see here you make the driver to initialize before probe, > >>> But I have no idea of why you do this change..... > >>> > >>> and I look inside the code, it may be pm_runtime relate?? > > Yes, it is related to runtime PM. In the PCI subsystem, runtime PM > > doesn't do anything unless pci_dev->driver is set. You can see this at > > the start of pci_pm_runtime_suspend(). > > > > Since we want the driver's probe routine to be able to carry out > > runtime PM operations, we have to set pci_dev->driver before the probe > > routine runs. > Is there any situations , like in probe state, pci_dev->driver > has been set. the pci_pm_runtime_xxx() has passed > pci_dev->driver NULL check, but at this point, probe fail > occurs, and pci_dev->driver to be set to NULL. > > What will happen ? Or this situation will never happen? > I'm confuse about this. I think that will never happen. Before ->probe(), pm_runtime_get_sync() is called, so pci_pm_runtime_xxx() will not be called until pm_runtime_put_noidle() is called in ->probe(). And pm_runtime_put_noidle() should be done as one of the latest actions in ->probe(), after the normal probe actions succeeded. Best Regards, Huang Ying -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
