From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wm0-x22c.google.com ([2a00:1450:400c:c09::22c]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aBmqc-00034h-AI for barebox@lists.infradead.org; Wed, 23 Dec 2015 17:05:11 +0000 Received: by mail-wm0-x22c.google.com with SMTP id l126so153744064wml.1 for ; Wed, 23 Dec 2015 09:04:50 -0800 (PST) Date: Wed, 23 Dec 2015 18:04:43 +0100 From: Alexander Aring Message-ID: <20151223170438.GA3791@omega> References: <20151223191058.4ffb07f4@berta> <20151223163532.GA1068@omega> <20151223195644.73537fb9@berta> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20151223195644.73537fb9@berta> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [RFC] device probe order To: Peter Mamonov Cc: barebox On Wed, Dec 23, 2015 at 07:56:44PM +0300, Peter Mamonov wrote: > On Wed, 23 Dec 2015 17:35:51 +0100 > Alexander Aring 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. 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