Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757356Ab3HMKpe (ORCPT ); Tue, 13 Aug 2013 06:45:34 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:45666 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757147Ab3HMKpb (ORCPT ); Tue, 13 Aug 2013 06:45:31 -0400 Message-ID: <520A0E1C.5000306@ti.com> Date: Tue, 13 Aug 2013 16:14:44 +0530 From: Kishon Vijay Abraham I User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: CC: Greg KH , Tomasz Figa , Alan Stern , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 01/15] drivers: phy: add generic PHY framework References: <20130720220006.GA7977@kroah.com> <3839600.WiC1OLF35o@flatron> <51EBC0F5.70601@ti.com> <9748041.Qq1fWJBg6D@flatron> <20130721154653.GG16598@kroah.com> <20130730071106.GC16441@radagast> <51F8A440.8010803@ti.com> <20130731061538.GC13289@radagast> In-Reply-To: <20130731061538.GC13289@radagast> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3913 Lines: 86 Hi, On Wednesday 31 July 2013 11:45 AM, Felipe Balbi wrote: > Hi, > > On Wed, Jul 31, 2013 at 11:14:32AM +0530, Kishon Vijay Abraham I wrote: >>>>>>> IMHO we need a lookup method for PHYs, just like for clocks, >>>>>>> regulators, PWMs or even i2c busses because there are complex cases >>>>>>> when passing just a name using platform data will not work. I would >>>>>>> second what Stephen said [1] and define a structure doing things in a >>>>>>> DT-like way. >>>>>>> >>>>>>> Example; >>>>>>> >>>>>>> [platform code] >>>>>>> >>>>>>> static const struct phy_lookup my_phy_lookup[] = { >>>>>>> >>>>>>> PHY_LOOKUP("s3c-hsotg.0", "otg", "samsung-usbphy.1", "phy.2"), >>>>>> >>>>>> The only problem here is that if *PLATFORM_DEVID_AUTO* is used while >>>>>> creating the device, the ids in the device name would change and >>>>>> PHY_LOOKUP wont be useful. >>>>> >>>>> I don't think this is a problem. All the existing lookup methods already >>>>> use ID to identify devices (see regulators, clkdev, PWMs, i2c, ...). You >>>>> can simply add a requirement that the ID must be assigned manually, >>>>> without using PLATFORM_DEVID_AUTO to use PHY lookup. >>>> >>>> And I'm saying that this idea, of using a specific name and id, is >>>> frought with fragility and will break in the future in various ways when >>>> devices get added to systems, making these strings constantly have to be >>>> kept up to date with different board configurations. >>>> >>>> People, NEVER, hardcode something like an id. The fact that this >>>> happens today with the clock code, doesn't make it right, it makes the >>>> clock code wrong. Others have already said that this is wrong there as >>>> well, as systems change and dynamic ids get used more and more. >>>> >>>> Let's not repeat the same mistakes of the past just because we refuse to >>>> learn from them... >>>> >>>> So again, the "find a phy by a string" functions should be removed, the >>>> device id should be automatically created by the phy core just to make >>>> things unique in sysfs, and no driver code should _ever_ be reliant on >>>> the number that is being created, and the pointer to the phy structure >>>> should be used everywhere instead. >>>> >>>> With those types of changes, I will consider merging this subsystem, but >>>> without them, sorry, I will not. >>> >>> I'll agree with Greg here, the very fact that we see people trying to >>> add a requirement of *NOT* using PLATFORM_DEVID_AUTO already points to a >>> big problem in the framework. >>> >>> The fact is that if we don't allow PLATFORM_DEVID_AUTO we will end up >>> adding similar infrastructure to the driver themselves to make sure we >>> don't end up with duplicate names in sysfs in case we have multiple >>> instances of the same IP in the SoC (or several of the same PCIe card). >>> I really don't want to go back to that. >> >> If we are using PLATFORM_DEVID_AUTO, then I dont see any way we can give the >> correct binding information to the PHY framework. I think we can drop having >> this non-dt support in PHY framework? I see only one platform (OMAP3) going to >> be needing this non-dt support and we can use the USB PHY library for it. > > you shouldn't drop support for non-DT platform, in any case we lived > without DT (and still do) for years. Gotta find a better way ;-) hmm.. how about passing the device names of PHY in platform data of the controller? It should be deterministic as the PHY framework assigns its own id and we *don't* want to add any requirement that the ID must be assigned manually without using PLATFORM_DEVID_AUTO. We can get rid of *phy_init_data* in the v10 patch series. Thanks Kishon > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/