From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640AbaCGFQj (ORCPT ); Fri, 7 Mar 2014 00:16:39 -0500 Received: from mailout4.samsung.com ([203.254.224.34]:43834 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751143AbaCGFQJ (ORCPT ); Fri, 7 Mar 2014 00:16:09 -0500 X-AuditID: cbfee68e-b7f566d000002344-05-531956164e7f From: Anton Tikhomirov To: "'Kishon Vijay Abraham I'" , "'Kamil Debski'" , linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-usb@vger.kernel.org, devicetree@vger.kernel.org Cc: kyungmin.park@samsung.com, t.figa@samsung.com, s.nawrocki@samsung.com, m.szyprowski@samsung.com, gautam.vivek@samsung.com, mat.krawczuk@gmail.com, yulgon.kim@samsung.com, p.paneri@samsung.com, jg1.han@samsung.com, galak@codeaurora.org, matt.porter@linaro.org, tjakobi@math.uni-bielefeld.de, stern@rowland.harvard.edu, sander@humilis.net References: <1394033288-5551-1-git-send-email-k.debski@samsung.com> <1394033288-5551-4-git-send-email-k.debski@samsung.com> <005c01cf3915$c53476c0$4f9d6440$%tikhomirov@samsung.com> <53183220.3040606@ti.com> <006201cf3919$5f760750$1e6215f0$%tikhomirov@samsung.com> <5318384B.7020009@ti.com> <006301cf391a$c99c7280$5cd55780$%tikhomirov@samsung.com> <006501cf391d$335fb9a0$9a1f2ce0$%tikhomirov@samsung.com> <53183F98.1060100@ti.com> In-reply-to: <53183F98.1060100@ti.com> Subject: RE: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY driver Date: Fri, 07 Mar 2014 14:16:06 +0900 Message-id: <003c01cf39c4$57aa8540$06ff8fc0$%tikhomirov@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=Windows-1252 Content-transfer-encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-index: Ac85Hq62Cp4mKTqOQmiRHIw1Z7nQVwApVdiQ Content-language: en-us X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrBKsWRmVeSWpSXmKPExsVy+t8zY12xMMlgg83zLSzmHznHatH/ZiGr RduVg+wWlxdeYrX48foCm8WFpz1sFmeb3gDFds1hs5hxfh+TxaJlrcwWa4/cZbc423+bzWJi 0zR2i/NbOpksDr9pZ7VYcW83u8WE30C962e8ZrFoW/2B1aLj7EF2BxGPy329TB47Z91l9/j0 djGzx51re9g8/h1j95h99wejR9+WVYwex29sZ/L4vEkugDOKyyYlNSezLLVI3y6BK+PBu7ss BfuVKhZffcDYwHhNuouRk0NCwETidMNBRghbTOLCvfVsXYxcHEICyxgldhxuYYEp+rX+EDNE YhGjxJYdUxghnH+MEgcPvAFrZxMwknh5cCNYlYjARUaJqdP3glUxC9xhkvgyfx8TRMteZok9 H84zgbRwCqhJ/LmzmQ3EFhZwkrjwvBEsziKgKrHifQNQNwcHr4CLxN8nZiBhXgFBiR+T74Hd xCygJ/Hxz21GCFteYvOat8wg5RIC6hKP/uqChEWADrq2YBozRIm4xKQHD9lBTpAQ+MAhsfvI ThaIVQIS3yYfYoHolZXYdIAZ4mVJiYMrbrBMYJSYhWTzLCSbZyHZPAvJigWMLKsYRVMLkguK k9KLjPSKE3OLS/PS9ZLzczcxQlJN3w7GmwesDzEmA62fyCwlmpwPTFV5JfGGxmZGFqYmpsZG 5pZmpAkrifMuepgUJCSQnliSmp2aWpBaFF9UmpNafIiRiYNTqoFRcIMv90cWniobwY235p14 7lKv+uWA4+aDzIr3fk78H/TR8YfVa6ZnF4LYZyf3TF33s8LF/3efx0H309qRDsoBfbE8V1WP FBz8JeMbPy1EjHP9XbmNNj4Ldx6Wtmopst8mqRkUNZXrgcFGn9qG7OvnCqfpv9HVXW4bKq6w muV9p4TII+XEwgIlluKMREMt5qLiRAC42ZIgSwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprKJsWRmVeSWpSXmKPExsVy+t9jAV2xMMlgg+5Vhhbzj5xjteh/s5DV ou3KQXaLywsvsVr8eH2BzeLC0x42i7NNb4Biu+awWcw4v4/JYtGyVmaLtUfusluc7b/NZjGx aRq7xfktnUwWh9+0s1qsuLeb3WLCb6De9TNes1i0rf7AatFx9iC7g4jH5b5eJo+ds+6ye3x6 u5jZ4861PWwe/46xe8y++4PRo2/LKkaP4ze2M3l83iQXwBnVwGiTkZqYklqkkJqXnJ+SmZdu q+QdHO8cb2pmYKhraGlhrqSQl5ibaqvk4hOg65aZA/SbkkJZYk4pUCggsbhYSd8O04TQEDdd C5jGCF3fkCC4HiMDNJCwjjHjwbu7LAX7lSoWX33A2MB4TbqLkZNDQsBE4tf6Q8wQtpjEhXvr 2boYuTiEBBYxSmzZMYURwvnHKHHwwBtGkCo2ASOJlwc3MoMkRAQuMkpMnb4XrIpZ4A6TxJf5 +5ggWvYyS+z5cJ4JpIVTQE3iz53NbCC2sICTxIXnjWBxFgFViRXvG4C6OTh4BVwk/j4xAwnz CghK/Jh8jwXEZhbQk/j45zYjhC0vsXnNW2aQcgkBdYlHf3VBwiJAB11bMI0ZokRcYtKDh+wT GIVmIZk0C8mkWUgmzULSsoCRZRWjaGpBckFxUnqukV5xYm5xaV66XnJ+7iZGcCJ7Jr2DcVWD xSFGAQ5GJR7ejkUSwUKsiWXFlbmHGCU4mJVEeI0DJYOFeFMSK6tSi/Lji0pzUosPMSYD/TmR WUo0OR+YZPNK4g2NTcyMLI3MLIxMzM1JE1YS5z3Yah0oJJCeWJKanZpakFoEs4WJg1OqgdEr ZMJVWcNqBonDkfcnvnzNt/1OZuiDULH2Gf1XjlXPU7nrrFgjP+vW+vZkjulnCz+kaJ4r/qK5 ek3N4YDSayURqtOsYsU02o4nMHYXK5pNVJSP3SU3z15XuODf160hfySPvLNVCHw2d+n6xW0y xa3+TNM3izkcVOy5P0+Xe+6xM9evHM+7bqjEUpyRaKjFXFScCADve0GcqAMAAA== DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, > Subject: Re: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY driver > > Hi, > > On Thursday 06 March 2014 02:49 PM, Anton Tikhomirov wrote: > > Hi, > > > >> Subject: RE: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY driver > >> > >> Hi, > >> > >>> Subject: Re: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY driver > >>> > >>> Hi, > >>> > >>> On Thursday 06 March 2014 02:22 PM, Anton Tikhomirov wrote: > >>>> Hello, > >>>> > >>>>> Subject: Re: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY > driver > >>>>> > >>>>> > >>>>> > >>>>> On Thursday 06 March 2014 01:56 PM, Anton Tikhomirov wrote: > >>>>>> Hi Kamil, > >>>>>> > >>>>>> ... > >>>>>> > >>>>>>> +| 3. Supporting SoCs > >>>>>>> ++-------------------- > >>>>>>> + > >>>>>>> +To support a new SoC a new file should be added to the > >>> drivers/phy > >>>>>>> +directory. Each SoC's configuration is stored in an instance > of > >>> the > >>>>>>> +struct samsung_usb2_phy_config. > >>>>>>> + > >>>>>>> +struct samsung_usb2_phy_config { > >>>>>>> + const struct samsung_usb2_common_phy *phys; > >>>>>>> + unsigned int num_phys; > >>>>>>> + bool has_mode_switch; > >>>>>> > >>>>>> You missed rate_to_clk here. > >>>>>> > >>>>>>> +}; > >>>>>>> + > >>>>>> > >>>>>> ... > >>>>>> > >>>>>>> diff --git a/drivers/phy/phy-samsung-usb2.c b/drivers/phy/phy- > >>>>> samsung- > >>>>>>> usb2.c > >>>>>>> new file mode 100644 > >>>>>>> index 0000000..c3b7719 > >>>>>>> --- /dev/null > >>>>>>> +++ b/drivers/phy/phy-samsung-usb2.c > >>>>>>> @@ -0,0 +1,222 @@ > >>>>>>> +/* > >>>>>>> + * Samsung SoC USB 1.1/2.0 PHY driver > >>>>>>> + * > >>>>>>> + * Copyright (C) 2013 Samsung Electronics Co., Ltd. > >>>>>>> + * Author: Kamil Debski > >>>>>>> + * > >>>>>>> + * This program is free software; you can redistribute it > >> and/or > >>>>>>> modify > >>>>>>> + * it under the terms of the GNU General Public License > version > >> 2 > >>>>> as > >>>>>>> + * published by the Free Software Foundation. > >>>>>>> + */ > >>>>>>> + > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include > >>>>>>> +#include "phy-samsung-usb2.h" > >>>>>>> + > >>>>>>> +static int samsung_usb2_phy_power_on(struct phy *phy) > >>>>>>> +{ > >>>>>>> + struct samsung_usb2_phy_instance *inst = > >>> phy_get_drvdata(phy); > >>>>>>> + struct samsung_usb2_phy_driver *drv = inst->drv; > >>>>>>> + int ret; > >>>>>>> + > >>>>>>> + dev_dbg(drv->dev, "Request to power_on \"%s\" usb phy\n", > >>>>>>> + inst->cfg->label); > >>>>>>> + ret = clk_prepare_enable(drv->clk); > >>>>>> > >>>>>> clk_prepare_enable() can sleep, and therefore doesn't allow > >>>>>> samusng_usb2_phy_power_on() to be used in atomic context > >>>>>> (e.g. inside spin_lock-ed area), what sometimes may be desirable. > >>>>>> What about to prepare clock in probe, and just enable it here > >>>>>> (note: clk_enable() doesn't sleep). > >>>>> > >>>>> The PHY power-on callback is anyway called with mutex held, so I > >>> guess > >>>>> it's fine to have clk_prepare_enable() here. > >>>> > >>>> If we rely totally on generic PHY functions such as phy_power_on() > >>>> and friends, why do we need to use locking in callbacks at all. > >>> > >>> Didn't get you.. We don't want to invoke power_on when init is > >> getting > >>> executed or you don't want power on or power off to get executed > >>> simultaneously right? So we need to protect it. > >> > >> I mean callbacks such as samsung_usb2_phy_power_on() which uses > >> spin_lock. > >> It's already protected by mutex in phy_power_on(). > > > > Well... phy_power_on() uses mutex to protect power_on() callback. > > power_on() is samsung_usb2_phy_power_on() in our case. > > samsung_usb2_phy_power_on() uses spinlock. > > My question is why do we need to use spinlock _inside_ callback > > if it is already protected by mutex. > > It is needed when the same PHY provider implements multiple PHYs. > phy-core can protect phy-ops of same PHY. However if the PHY provider > implements multiple PHYs, phy-core won't be able to protect. Thank you Kishon. Now it's clear.