Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Wed, 20 Feb 2019 11:51:01 +0100 | Subject | Re: [PATCH] platform: set of_node in platform_device_register_full() |
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On Wed, Feb 20, 2019 at 11:41 AM Måns Rullgård <mans@mansr.com> wrote: > > "Rafael J. Wysocki" <rafael@kernel.org> writes: > > > On Mon, Feb 18, 2019 at 12:10 PM Måns Rullgård <mans@mansr.com> wrote: > >> > >> "Rafael J. Wysocki" <rafael@kernel.org> writes: > >> > >> > On Sat, Feb 16, 2019 at 5:50 PM Mans Rullgard <mans@mansr.com> wrote: > >> >> > >> >> If the provided fwnode is an OF node, set dev.of_node as well. > >> >> > >> >> Signed-off-by: Mans Rullgard <mans@mansr.com> > >> >> --- > >> >> drivers/base/platform.c | 1 + > >> >> 1 file changed, 1 insertion(+) > >> >> > >> >> diff --git a/drivers/base/platform.c b/drivers/base/platform.c > >> >> index dff82a3c2caa..853a1d0e5845 100644 > >> >> --- a/drivers/base/platform.c > >> >> +++ b/drivers/base/platform.c > >> >> @@ -512,6 +512,7 @@ struct platform_device *platform_device_register_full( > >> >> > >> >> pdev->dev.parent = pdevinfo->parent; > >> >> pdev->dev.fwnode = pdevinfo->fwnode; > >> >> + pdev->dev.of_node = of_node_get(to_of_node(pdev->dev.fwnode)); > >> > > >> > of_node_get() generally does a kobject_get() on the node's kobject, so > >> > when is that reference dropped? Or if it doesn't need to be dropped > >> > at all, why is this the case? > >> > >> platform_device_release() calls of_device_node_put(). > > > > Yes, it does, but this is the reference that's already acquired for > > devices added while parsing DT, isn't it? > > > > Your change adds an extra reference AFAICS. > > > > Also, why is this patch needed? > > Some drivers are just shims that create extra "glue" devices with the DT > device as parent and have the real driver bind to these. In other > cases, the same real driver matches the DT node directly. When a glue > device is used, it needs to get a reference to the original DT node in > order for the main driver to access properties and child nodes. > > Right now, my problem is that the suxi-musb driver creates such a glue > device for the musb core driver to bind to without setting of_node. > This means devices attached to this USB interface don't get associated > with DT nodes, if present, the way they do with EHCI.
You really should describe problems that you want to address in patch changelogs. This helps a lot to understand the motivation for the changes.
> The sunxi-musb driver uses platform_device_register_full(), so this > seemed like the easiest way to let it set of_node of the new device. > Since this creates a second reference to the same node, of_node_get() > is required.
But what about devices that already have of_node set at this point?
Maybe check if of_node is NULL before trying to set it?
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