[RFC] device probe order

[Peter Mamonov]

On Wed, 23 Dec 2015 17:35:51 +0100
Alexander Aring <alex.aring at gmail.com> wrote:

> 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?
> > 
> 
> Normally this should done by returning "-EPROBE_DEFER" inside the
> probe function. There was some RFC last years for supporting
> EPROBE_DEFER [0] and it seems these are mainline.
> 
> However you need some bool which indicates that the EHCI driver is
> probed.

Thanks, Alex. As i understand, this is the linux-way solution.

Sasha, is it ok to add a global variable to indicate the EHCI presence?
Or should we follow the way proposed by the mentioned RFCs, i.e.
introduce dependencies between drivers?

> 
> int uhci_probe(foobar) {
> 
> if (!indicate_ehci_is_probed(foobar)
> 	return -EPROBE_DEFER;
> }
> 
> - Alex
> 
> [0]
> http://barebox.infradead.narkive.com/ZWIXXU0R/patch-v2-0-6-introduce-deferred-probing