From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755205Ab3GUKbM (ORCPT ); Sun, 21 Jul 2013 06:31:12 -0400 Received: from mail-bk0-f45.google.com ([209.85.214.45]:64364 "EHLO mail-bk0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754542Ab3GUKbK (ORCPT ); Sun, 21 Jul 2013 06:31:10 -0400 From: Tomasz Figa To: Greg KH Cc: Alan Stern , Kishon Vijay Abraham I , kyungmin.park@samsung.com, balbi@ti.com, jg1.han@samsung.com, s.nawrocki@samsung.com, kgene.kim@samsung.com, grant.likely@linaro.org, tony@atomide.com, arnd@arndb.de, swarren@nvidia.com, devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-omap@vger.kernel.org, linux-usb@vger.kernel.org, linux-media@vger.kernel.org, linux-fbdev@vger.kernel.org, akpm@linux-foundation.org, balajitk@ti.com, george.cherian@ti.com, nsekhar@ti.com Subject: Re: [PATCH 01/15] drivers: phy: add generic PHY framework Date: Sun, 21 Jul 2013 12:31:05 +0200 Message-ID: <3839600.WiC1OLF35o@flatron> User-Agent: KMail/4.10.5 (Linux/3.10.1-gentoo; KDE/4.10.5; x86_64; ; ) In-Reply-To: <20130721025910.GA23043@kroah.com> References: <20130720220006.GA7977@kroah.com> <20130721025910.GA23043@kroah.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Saturday 20 of July 2013 19:59:10 Greg KH wrote: > On Sat, Jul 20, 2013 at 10:32:26PM -0400, Alan Stern wrote: > > On Sat, 20 Jul 2013, Greg KH wrote: > > > > >>That should be passed using platform data. > > > > > > > > > >Ick, don't pass strings around, pass pointers. If you have > > > > >platform > > > > >data you can get to, then put the pointer there, don't use a > > > > >"name". > > > > > > > > I don't think I understood you here :-s We wont have phy pointer > > > > when we create the device for the controller no?(it'll be done in > > > > board file). Probably I'm missing something. > > > > > > Why will you not have that pointer? You can't rely on the "name" as > > > the device id will not match up, so you should be able to rely on > > > the pointer being in the structure that the board sets up, right? > > > > > > Don't use names, especially as ids can, and will, change, that is > > > going > > > to cause big problems. Use pointers, this is C, we are supposed to > > > be > > > doing that :) > > > > Kishon, I think what Greg means is this: The name you are using must > > be stored somewhere in a data structure constructed by the board file, > > right? Or at least, associated with some data structure somehow. > > Otherwise the platform code wouldn't know which PHY hardware > > corresponded to a particular name. > > > > Greg's suggestion is that you store the address of that data structure > > in the platform data instead of storing the name string. Have the > > consumer pass the data structure's address when it calls phy_create, > > instead of passing the name. Then you don't have to worry about two > > PHYs accidentally ending up with the same name or any other similar > > problems. > > Close, but the issue is that whatever returns from phy_create() should > then be used, no need to call any "find" functions, as you can just use > the pointer that phy_create() returns. Much like all other class api > functions in the kernel work. I think there is a confusion here about who registers the PHYs. All platform code does is registering a platform/i2c/whatever device, which causes a driver (located in drivers/phy/) to be instantiated. Such drivers call phy_create(), usually in their probe() callbacks, so platform_code has no way (and should have no way, for the sake of layering) to get what phy_create() returns. 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"), /* etc... */ }; static void my_machine_init(void) { /* ... */ phy_register_lookup(my_phy_lookup, ARRAY_SIZE(my_phy_lookup)); /* ... */ } /* Notice nothing stuffed in platform data. */ [provider code - samsung-usbphy driver] static int samsung_usbphy_probe(...) { /* ... */ for (i = 0; i < PHY_COUNT; ++i) { usbphy->phy[i].name = "phy"; usbphy->phy[i].id = i; /* ... */ ret = phy_create(&usbphy->phy); /* err handling */ } /* ... */ } [consumer code - s3c-hsotg driver] static int s3c_hsotg_probe(...) { /* ... */ phy = phy_get(&pdev->dev, "otg"); /* ... */ } [1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/252813 Best regards, Tomasz From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Figa Date: Sun, 21 Jul 2013 10:31:05 +0000 Subject: Re: [PATCH 01/15] drivers: phy: add generic PHY framework Message-Id: <3839600.WiC1OLF35o@flatron> List-Id: References: <20130720220006.GA7977@kroah.com> <20130721025910.GA23043@kroah.com> In-Reply-To: <20130721025910.GA23043@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org Hi, On Saturday 20 of July 2013 19:59:10 Greg KH wrote: > On Sat, Jul 20, 2013 at 10:32:26PM -0400, Alan Stern wrote: > > On Sat, 20 Jul 2013, Greg KH wrote: > > > > >>That should be passed using platform data. > > > > > > > > > >Ick, don't pass strings around, pass pointers. If you have > > > > >platform > > > > >data you can get to, then put the pointer there, don't use a > > > > >"name". > > > > > > > > I don't think I understood you here :-s We wont have phy pointer > > > > when we create the device for the controller no?(it'll be done in > > > > board file). Probably I'm missing something. > > > > > > Why will you not have that pointer? You can't rely on the "name" as > > > the device id will not match up, so you should be able to rely on > > > the pointer being in the structure that the board sets up, right? > > > > > > Don't use names, especially as ids can, and will, change, that is > > > going > > > to cause big problems. Use pointers, this is C, we are supposed to > > > be > > > doing that :) > > > > Kishon, I think what Greg means is this: The name you are using must > > be stored somewhere in a data structure constructed by the board file, > > right? Or at least, associated with some data structure somehow. > > Otherwise the platform code wouldn't know which PHY hardware > > corresponded to a particular name. > > > > Greg's suggestion is that you store the address of that data structure > > in the platform data instead of storing the name string. Have the > > consumer pass the data structure's address when it calls phy_create, > > instead of passing the name. Then you don't have to worry about two > > PHYs accidentally ending up with the same name or any other similar > > problems. > > Close, but the issue is that whatever returns from phy_create() should > then be used, no need to call any "find" functions, as you can just use > the pointer that phy_create() returns. Much like all other class api > functions in the kernel work. I think there is a confusion here about who registers the PHYs. All platform code does is registering a platform/i2c/whatever device, which causes a driver (located in drivers/phy/) to be instantiated. Such drivers call phy_create(), usually in their probe() callbacks, so platform_code has no way (and should have no way, for the sake of layering) to get what phy_create() returns. 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"), /* etc... */ }; static void my_machine_init(void) { /* ... */ phy_register_lookup(my_phy_lookup, ARRAY_SIZE(my_phy_lookup)); /* ... */ } /* Notice nothing stuffed in platform data. */ [provider code - samsung-usbphy driver] static int samsung_usbphy_probe(...) { /* ... */ for (i = 0; i < PHY_COUNT; ++i) { usbphy->phy[i].name = "phy"; usbphy->phy[i].id = i; /* ... */ ret = phy_create(&usbphy->phy); /* err handling */ } /* ... */ } [consumer code - s3c-hsotg driver] static int s3c_hsotg_probe(...) { /* ... */ phy = phy_get(&pdev->dev, "otg"); /* ... */ } [1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/252813 Best regards, Tomasz From mboxrd@z Thu Jan 1 00:00:00 1970 From: tomasz.figa@gmail.com (Tomasz Figa) Date: Sun, 21 Jul 2013 12:31:05 +0200 Subject: [PATCH 01/15] drivers: phy: add generic PHY framework In-Reply-To: <20130721025910.GA23043@kroah.com> References: <20130720220006.GA7977@kroah.com> <20130721025910.GA23043@kroah.com> Message-ID: <3839600.WiC1OLF35o@flatron> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Saturday 20 of July 2013 19:59:10 Greg KH wrote: > On Sat, Jul 20, 2013 at 10:32:26PM -0400, Alan Stern wrote: > > On Sat, 20 Jul 2013, Greg KH wrote: > > > > >>That should be passed using platform data. > > > > > > > > > >Ick, don't pass strings around, pass pointers. If you have > > > > >platform > > > > >data you can get to, then put the pointer there, don't use a > > > > >"name". > > > > > > > > I don't think I understood you here :-s We wont have phy pointer > > > > when we create the device for the controller no?(it'll be done in > > > > board file). Probably I'm missing something. > > > > > > Why will you not have that pointer? You can't rely on the "name" as > > > the device id will not match up, so you should be able to rely on > > > the pointer being in the structure that the board sets up, right? > > > > > > Don't use names, especially as ids can, and will, change, that is > > > going > > > to cause big problems. Use pointers, this is C, we are supposed to > > > be > > > doing that :) > > > > Kishon, I think what Greg means is this: The name you are using must > > be stored somewhere in a data structure constructed by the board file, > > right? Or at least, associated with some data structure somehow. > > Otherwise the platform code wouldn't know which PHY hardware > > corresponded to a particular name. > > > > Greg's suggestion is that you store the address of that data structure > > in the platform data instead of storing the name string. Have the > > consumer pass the data structure's address when it calls phy_create, > > instead of passing the name. Then you don't have to worry about two > > PHYs accidentally ending up with the same name or any other similar > > problems. > > Close, but the issue is that whatever returns from phy_create() should > then be used, no need to call any "find" functions, as you can just use > the pointer that phy_create() returns. Much like all other class api > functions in the kernel work. I think there is a confusion here about who registers the PHYs. All platform code does is registering a platform/i2c/whatever device, which causes a driver (located in drivers/phy/) to be instantiated. Such drivers call phy_create(), usually in their probe() callbacks, so platform_code has no way (and should have no way, for the sake of layering) to get what phy_create() returns. 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"), /* etc... */ }; static void my_machine_init(void) { /* ... */ phy_register_lookup(my_phy_lookup, ARRAY_SIZE(my_phy_lookup)); /* ... */ } /* Notice nothing stuffed in platform data. */ [provider code - samsung-usbphy driver] static int samsung_usbphy_probe(...) { /* ... */ for (i = 0; i < PHY_COUNT; ++i) { usbphy->phy[i].name = "phy"; usbphy->phy[i].id = i; /* ... */ ret = phy_create(&usbphy->phy); /* err handling */ } /* ... */ } [consumer code - s3c-hsotg driver] static int s3c_hsotg_probe(...) { /* ... */ phy = phy_get(&pdev->dev, "otg"); /* ... */ } [1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/252813 Best regards, Tomasz