[RFC] device probe order

[Peter Mamonov]

On Wed, 23 Dec 2015 20:46:02 +0100
Sascha Hauer <s.hauer at pengutronix.de> wrote:

> Hi Peter,
> 
> On Wed, Dec 23, 2015 at 07:10:58PM +0300, Peter Mamonov wrote:
> > Dear All,
> > 
> > I've ported an UHCI driver from the u-boot to the barebox (WIP). To
> > interoperate with the EHCI driver, the UHCI driver should be probed
> > ater the EHCI driver. Both drivers are binded via the device tree
> > mechanism. How can i achieve the correct probe order?
> 
> Do you have an example binding to look at? Normally I would assume
> that the binding makes sure somehow that the uhci driver has to be
> probed.


At the moment the binding is quite straightforward:

		ehci: ehci at 1ba00200 {
			compatible = "generic-ehci";
			reg = <0x00000000 0x20 0x00000000 0x100>;
			status = "disabled";
		};

		uhci: uhci at 1ba00000 {
			compatible = "generic-uhci";
			reg = <0x00000000 0x200>;
			status = "disabled";
		};

Probably, we can add "companion = <&ehci>;" into the uhci node and
check if the ehci has been probed by calling of_find_device_by_node(),
as  Alexander Aring proposed.

> 
> Sascha
> 
>