On Thu, Apr 13, 2023 at 07:00:26PM +0300, Andy Shevchenko wrote: > On Wed, Apr 12, 2023 at 11:02:53AM -0500, Bjorn Helgaas wrote: > > On Wed, Apr 12, 2023 at 04:15:20PM +0300, Andy Shevchenko wrote: > > > Propagate firmware node by using a specific API call, i.e. device_set_node(). > > > > Can you add a line or two about *why* we should do this, e.g., is this > > headed toward some goal? > > Because dereferencing the fwnode in struct device is preventing us from > modifications of how fwnode looks like in the future. How do you want to express this in the commit log? Something like this? Insulate pci_set_of_node() and pci_set_bus_of_node() from possible changes to fwnode_handle implementation by using device_set_node() instead of open-coding dev->dev.fwnode assignments. > > Is it a simplification that's 100% > > equivalent (doesn't seem so, see below)? > > To me it's an equivalent, I'll explain below. > > > Seems like there's an underlying long-term effort to unify things from > > OF and ACPI, which seems like a good thing, but at the moment it's a > > little confusing to follow. For instance pci_set_of_node() seems like > > it ought to be sort of analogous to pci_set_acpi_fwnode(), but they > > look nothing alike. > > Unification to some extent, but here is not a point of this change. > > ... > > > > + struct device_node *node; > > > + > > > if (!dev->bus->dev.of_node) > > > return; > > > - dev->dev.of_node = of_pci_find_child_device(dev->bus->dev.of_node, > > > - dev->devfn); > > > - if (dev->dev.of_node) > > > - dev->dev.fwnode = &dev->dev.of_node->fwnode; > > > + node = of_pci_find_child_device(dev->bus->dev.of_node, dev->devfn); > > > + device_set_node(&dev->dev, of_fwnode_handle(node)); > > > > This doesn't seem 100% equivalent. If of_pci_find_child_device() > > returns NULL, the previous code doesn't set dev->dev.fwnode, but the > > new code does. > > Yes and this is not a problem. We create device with pci_alloc_dev() in both > callers of the pci_setup_device() and the field is NULL anyway. So, the last > condition there is a simple micro-optimisation. OK, makes sense, thanks. Bjorn
