Re: [PATCH] platform: set of_node in platform_device_register_full()

From: Måns Rullgård
Date: Wed Feb 20 2019 - 07:12:38 EST

Johan Hovold <johan@xxxxxxxxxx> writes:

> On Wed, Feb 20, 2019 at 11:35:06AM +0000, Mans Rullgard wrote:
>> If the provided fwnode is an OF node, set dev.of_node as well.
>> 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 these
>> cases, the glue device needs to get a reference to the original DT node
>> in order for the main driver to access properties and child nodes.
>> For example, the sunxi-musb driver creates such a glue device using
>> platform_device_register_full(). Consequently, devices attached to
>> this USB interface don't get associated with DT nodes, if present,
>> the way they do with EHCI.
>> This change will allow sunxi-musb and similar driver to easily
>> propagate the DT node to child devices as required.
> Just a drive-by comment, didn't look to closely at this patch, but this
> all sounds familiar.
> Note that if both platform devices are bound to drivers you may end up
> with some resources like pinctrl which are handled automatically by
> driver core at probe time to be requested twice (and failing the second
> time).
> Take a look at 4e75e1d7dac9 ("driver core: add helper to reuse a
> device-tree node"), which provides a means to avoid this, and
> 49484abd93ab ("USB: musb: dsps: propagate device-tree node").

Thanks, and ugh. So we should be setting the of_node_reused flag when
this is the case. It's easy for the musb-dsps driver since it doesn't
use platform_device_register_full() and can do this before the
device_add() call. How can we convey that this flag needs to be set?

>> Signed-off-by: Mans Rullgard <mans@xxxxxxxxx>
>> ---
>> 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));
>> if (pdevinfo->dma_mask) {
>> /*
> Johan

Måns Rullgård