From: Peter Mamonov <pmamonov@gmail.com>
To: Alexander Aring <alex.aring@gmail.com>
Cc: barebox <barebox@lists.infradead.org>
Subject: Re: [RFC] device probe order
Date: Thu, 24 Dec 2015 16:42:25 +0300 [thread overview]
Message-ID: <20151224164225.25665d7f@berta> (raw)
In-Reply-To: <20151224124837.0fcc6fce@berta>
On Thu, 24 Dec 2015 12:48:37 +0300
Peter Mamonov <pmamonov@gmail.com> wrote:
> On Wed, 23 Dec 2015 18:04:43 +0100
> Alexander Aring <alex.aring@gmail.com> wrote:
>
> > On Wed, Dec 23, 2015 at 07:56:44PM +0300, Peter Mamonov wrote:
> > > On Wed, 23 Dec 2015 17:35:51 +0100
> > > Alexander Aring <alex.aring@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?
> > >
> >
> > mhhh, maybe a simple "get_device_by_name" works here.
> >
> > If returning NULL then return -EPROBE_DEFER. Don't know if this is a
> > good solution, name need to be unique then.
> >
> >
> > btw:
> > Just found that "of_find_device_by_node" returns -EPROBE_DEFER when
> > nothing was found. This was introduced by the patch series.
>
> I like this approach better, than introducing a global variable.
> Will look further into it.
Unfortunately of_find_device_by_node() returns a valid pointer to
the device before the device probe function is called. I guess
get_device_by_name() behaves in the same way.
>
> >
> > Maybe it helps to look how the current use-cases deals with
> > -EPROBE_DEFER or get_device_by_name is enough.
> >
> > - Alex
> >
>
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
next prev parent reply other threads:[~2015-12-24 13:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-23 16:10 Peter Mamonov
2015-12-23 16:35 ` Alexander Aring
2015-12-23 16:56 ` Peter Mamonov
2015-12-23 17:04 ` Alexander Aring
2015-12-24 9:48 ` Peter Mamonov
2015-12-24 13:42 ` Peter Mamonov [this message]
2016-01-04 8:56 ` Sascha Hauer
2015-12-23 19:46 ` Sascha Hauer
2015-12-24 10:46 ` Peter Mamonov
2015-12-24 14:35 ` Alexander Aring
2015-12-24 16:10 ` Peter Mamonov
2015-12-25 10:21 ` Alexander Aring
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151224164225.25665d7f@berta \
--to=pmamonov@gmail.com \
--cc=alex.aring@gmail.com \
--cc=barebox@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox