From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kishon Vijay Abraham I Subject: Re: [PATCH 01/15] drivers: phy: add generic PHY framework Date: Sat, 20 Jul 2013 08:45:29 +0530 Message-ID: <51EA00D1.7080402@ti.com> References: <1374129984-765-1-git-send-email-kishon@ti.com> <1374129984-765-2-git-send-email-kishon@ti.com> <20130718072004.GA16720@kroah.com> <51E7AE88.3050007@ti.com> <20130718154954.GA31961@kroah.com> <51E8D086.809@ti.com> <20130719054311.GA14638@kroah.com> <51E8D4E0.8060200@ti.com> <20130719062941.GA23611@kroah.com> <51E8DE51.1060404@ti.com> <51E96135.9090108@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51E96135.9090108-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Stephen Warren Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kgene.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, balajitk-l0cyMroinI0@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Greg KH , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, jg1.han-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, nsekhar-l0cyMroinI0@public.gmane.org, george.cherian-l0cyMroinI0@public.gmane.org, balbi-l0cyMroinI0@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, s.nawrocki-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi, On Friday 19 July 2013 09:24 PM, Stephen Warren wrote: > On 07/19/2013 12:36 AM, Kishon Vijay Abraham I wrote: >> Hi, >> >> On Friday 19 July 2013 11:59 AM, Greg KH wrote: >>> On Fri, Jul 19, 2013 at 11:25:44AM +0530, Kishon Vijay Abraham I wrote: >>>> Hi, >>>> >>>> On Friday 19 July 2013 11:13 AM, Greg KH wrote: >>>>> On Fri, Jul 19, 2013 at 11:07:10AM +0530, Kishon Vijay Abraham I wrote: >>>>>>>>>> + ret = dev_set_name(&phy->dev, "%s.%d", dev_name(dev), id); >>>>>>>>> >>>>>>>>> Your naming is odd, no "phy" anywhere in it? You rely on the sender to >>>>>>>>> never send a duplicate name.id pair? Why not create your own ids based >>>>>>>>> on the number of phys in the system, like almost all other classes and >>>>>>>>> subsystems do? >>>>>>>> >>>>>>>> hmm.. some PHY drivers use the id they provide to perform some of their >>>>>>>> internal operation as in [1] (This is used only if a single PHY provider >>>>>>>> implements multiple PHYS). Probably I'll add an option like PLATFORM_DEVID_AUTO >>>>>>>> to give the PHY drivers an option to use auto id. >>>>>>>> >>>>>>>> [1] -> >>>>>>>> http://archive.arm.linux.org.uk/lurker/message/20130628.134308.4a8f7668.ca.html >>>>>>> >>>>>>> No, who cares about the id? No one outside of the phy core ever should, >>>>>>> because you pass back the only pointer that they really do care about, >>>>>>> if they need to do anything with the device. Use that, and then you can >>>>>> >>>>>> hmm.. ok. >>>>>> >>>>>>> rip out all of the "search for a phy by a string" logic, as that's not >>>>>> >>>>>> Actually this is needed for non-dt boot case. In the case of dt boot, we use a >>>>>> phandle by which the controller can get a reference to the phy. But in the case >>>>>> of non-dt boot, the controller can get a reference to the phy only by label. >>>>> >>>>> I don't understand. They registered the phy, and got back a pointer to >>>>> it. Why can't they save it in their local structure to use it again >>>>> later if needed? They should never have to "ask" for the device, as the >>>> >>>> One is a *PHY provider* driver which is a driver for some PHY device. This will >>>> use phy_create to create the phy. >>>> The other is a *PHY consumer* driver which might be any controller driver (can >>>> be USB/SATA/PCIE). The PHY consumer will use phy_get to get a reference to the >>>> phy (by *phandle* in the case of dt boot and *label* in the case of non-dt boot). >>>>> device id might be unknown if there are multiple devices in the system. >>>> >>>> I agree with you on the device id part. That need not be known to the PHY driver. >>> >>> How does a consumer know which "label" to use in a non-dt system if >>> there are multiple PHYs in the system? >> >> That should be passed using platform data. > > I don't think that's right. That's just like passing clock names in > platform data, which I believe is frowned upon. > > Instead, why not take the approach that e.g. regulators have taken? Each > driver defines the names of the objects that it requires. There is a > table (registered by a board file) that has lookup key (device name, We were using a similar approach with USB PHY layer but things started breaking after the device names are created using PLATFORM_DEVID_AUTO. Now theres no way to reliably know the device names in advance. Btw I had such device name binding in my v3 of this patch series [1] and had some discussion with Grant during that time [2]. [1] -> http://archive.arm.linux.org.uk/lurker/message/20130320.091200.721a6fb5.hu.html [2] -> https://lkml.org/lkml/2013/4/22/26 Thanks Kishon