| Message ID | 20230412131520.52840-1-andriy.shevchenko@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v1,1/1] PCI: of: Propagate firmware node | expand |
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? Is it a simplification that's 100% equivalent (doesn't seem so, see 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. > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > --- > drivers/pci/of.c | 19 +++++++------------ > 1 file changed, 7 insertions(+), 12 deletions(-) > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > index 196834ed44fe..4bba00dfbfc5 100644 > --- a/drivers/pci/of.c > +++ b/drivers/pci/of.c > @@ -18,19 +18,18 @@ > #ifdef CONFIG_PCI > void pci_set_of_node(struct pci_dev *dev) > { > + 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. > } > > void pci_release_of_node(struct pci_dev *dev) > { > of_node_put(dev->dev.of_node); > - dev->dev.of_node = NULL; > - dev->dev.fwnode = NULL; > + device_set_node(&dev->dev, NULL); > } > > void pci_set_bus_of_node(struct pci_bus *bus) > @@ -45,17 +44,13 @@ void pci_set_bus_of_node(struct pci_bus *bus) > bus->self->external_facing = true; > } > > - bus->dev.of_node = node; > - > - if (bus->dev.of_node) > - bus->dev.fwnode = &bus->dev.of_node->fwnode; > + device_set_node(&bus->dev, of_fwnode_handle(node)); > } > > void pci_release_bus_of_node(struct pci_bus *bus) > { > of_node_put(bus->dev.of_node); > - bus->dev.of_node = NULL; > - bus->dev.fwnode = NULL; > + device_set_node(&bus->dev, NULL); > } > > struct device_node * __weak pcibios_get_phb_of_node(struct pci_bus *bus) > -- > 2.40.0.1.gaa8946217a0b >
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. > 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.
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
On Fri, Apr 14, 2023 at 01:55:45PM -0500, Bjorn Helgaas wrote: > 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. Sounds good to me, thanks for the draft. I will do it in v2 this way.
diff --git a/drivers/pci/of.c b/drivers/pci/of.c index 196834ed44fe..4bba00dfbfc5 100644 --- a/drivers/pci/of.c +++ b/drivers/pci/of.c @@ -18,19 +18,18 @@ #ifdef CONFIG_PCI void pci_set_of_node(struct pci_dev *dev) { + 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)); } void pci_release_of_node(struct pci_dev *dev) { of_node_put(dev->dev.of_node); - dev->dev.of_node = NULL; - dev->dev.fwnode = NULL; + device_set_node(&dev->dev, NULL); } void pci_set_bus_of_node(struct pci_bus *bus) @@ -45,17 +44,13 @@ void pci_set_bus_of_node(struct pci_bus *bus) bus->self->external_facing = true; } - bus->dev.of_node = node; - - if (bus->dev.of_node) - bus->dev.fwnode = &bus->dev.of_node->fwnode; + device_set_node(&bus->dev, of_fwnode_handle(node)); } void pci_release_bus_of_node(struct pci_bus *bus) { of_node_put(bus->dev.of_node); - bus->dev.of_node = NULL; - bus->dev.fwnode = NULL; + device_set_node(&bus->dev, NULL); } struct device_node * __weak pcibios_get_phb_of_node(struct pci_bus *bus)
Propagate firmware node by using a specific API call, i.e. device_set_node(). Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- drivers/pci/of.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)