On Mon, Jul 13, 2020 at 07:38:14PM -0500, Bjorn Helgaas wrote:
> On Mon, Jul 13, 2020 at 12:01:51PM +0200, Hans Verkuil wrote:
> > On 29/06/2020 09:36, Vaibhav Gupta wrote:
> >
> > I don't entirely understand this. Wouldn't it be sufficient to just
> > drop the .suspend/.resume assignments here? It is now required for
> > driver.pm to be non-NULL?
> >
> > I'm not up to speed on the changes, but normally you can leave things
> > NULL if you don't support a feature (PM in this case).
>
> I think this patch will break things. Previously, we had:
>
> cx23885_pci_driver.suspend == NULL
> cx23885_pci_driver.resume == NULL
> cx23885_pci_driver.driver.pm == NULL
>
> pci_pm_suspend() looks like:
>
> if (pci_has_legacy_pm_support(pci_dev))
> return pci_legacy_suspend(dev, PMSG_SUSPEND);
>
> if (!pm) {
> pci_pm_default_suspend(pci_dev);
> return 0;
> }
>
> pci_has_legacy_pm_support() was false since drv->suspend and
> drv->resume are both NULL, so we'd take the pci_pm_default_suspend()
> path. After this patch, driver.pm would no longer be NULL, so we'd
> take a different path that is clearly not equivalent.
>
> I think you should do this:
>
> - /* TODO */
> - .suspend = NULL,
> - .resume = NULL,
>
> and leave .driver.pm NULL by not mentioning it at all. That should be
> identical at the object code level since those are the defaults
> anyway.
>
> That almost looks like useless churn, but the point of this patch is
> to remove use of PCI legacy PM (pci_driver.suspend and .resume) so we
> can completely remove that infrastructure from the PCI core, including
> the .suspend and .resume members of struct pci_driver, so we really do
> need to do it.
Okay!
Thanks!
-- Vaibhav Gupta
>
> Bjorn
