Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755058AbaDOOAf (ORCPT ); Tue, 15 Apr 2014 10:00:35 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:39591 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754810AbaDOOAa (ORCPT ); Tue, 15 Apr 2014 10:00:30 -0400 Message-ID: <534D3B58.8010606@ti.com> Date: Tue, 15 Apr 2014 19:29:52 +0530 From: Kishon Vijay Abraham I User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Tomasz Figa , Vivek Gautam , Mark Brown , Stephen Warren , , CC: Linux USB Mailing List , "linux-samsung-soc@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , , Greg KH , Felipe Balbi , Kukjin Kim , Tomasz Figa , Kamil Debski , Jingoo Han , Sylwester Nawrocki Subject: Re: [PATCH V4 1/5] phy: Add new Exynos5 USB 3.0 PHY driver References: <1396967803-28868-1-git-send-email-gautam.vivek@samsung.com> <1396967803-28868-2-git-send-email-gautam.vivek@samsung.com> <534BD447.1080909@ti.com> <534BDBBC.5010701@ti.com> <534BE200.8080009@ti.com> <534BE77E.5090902@gmail.com> In-Reply-To: <534BE77E.5090902@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Monday 14 April 2014 07:19 PM, Tomasz Figa wrote: > On 14.04.2014 15:40, Vivek Gautam wrote: >> On Mon, Apr 14, 2014 at 6:56 PM, Kishon Vijay Abraham I wrote: >>> >>> >>> On Monday 14 April 2014 06:50 PM, Vivek Gautam wrote: >>>> On Mon, Apr 14, 2014 at 6:29 PM, Kishon Vijay Abraham I wrote: >>>>> >>>>> >>>>> On Monday 14 April 2014 06:12 PM, Vivek Gautam wrote: >>>>>> Hi, >>>>>> >>>>>> >>>>>> On Mon, Apr 14, 2014 at 5:57 PM, Kishon Vijay Abraham I >>>>>> wrote: >>>>>>> Hi, >>>>>>> >>>>>>> On Tuesday 08 April 2014 08:06 PM, Vivek Gautam wrote: >>>>>>>> Add a new driver for the USB 3.0 PHY on Exynos5 series of SoCs. >>>>>>>> The new driver uses the generic PHY framework and will interact >>>>>>>> with DWC3 controller present on Exynos5 series of SoCs. >>>>>>>> Thereby, removing old phy-samsung-usb3 driver and related code >>>>>>>> used untill now which was based on usb/phy framework. >>>>>>>> >>>>>>>> Signed-off-by: Vivek Gautam >>>>>>>> --- >>>>>>>> .../devicetree/bindings/phy/samsung-phy.txt | 42 ++ >>>>>>>> drivers/phy/Kconfig | 11 + >>>>>>>> drivers/phy/Makefile | 1 + >>>>>>>> drivers/phy/phy-exynos5-usbdrd.c | 668 >>>>>>>> ++++++++++++++++++++ >>>>>>>> 4 files changed, 722 insertions(+) >>>>>>>> create mode 100644 drivers/phy/phy-exynos5-usbdrd.c >>>>>>>> >>>>>>>> diff --git a/Documentation/devicetree/bindings/phy/samsung-phy.txt >>>>>>>> b/Documentation/devicetree/bindings/phy/samsung-phy.txt >>>>>>>> index 28f9edb..6d99ba9 100644 >>>>>>>> --- a/Documentation/devicetree/bindings/phy/samsung-phy.txt >>>>>>>> +++ b/Documentation/devicetree/bindings/phy/samsung-phy.txt >>>>>>>> @@ -74,3 +74,45 @@ phy-consumer@12340000 { >>>>>>>> >>>>>>>> Refer to DT bindings documentation of particular PHY consumer devices >>>>>>>> for more >>>>>>>> information about required PHYs and the way of specification. >>>>>>>> + >>>>>>>> +Samsung Exynos5 SoC series USB DRD PHY controller >>>>>>>> +-------------------------------------------------- >>>>>>>> + >>>>>>>> +Required properties: >>>>>>>> +- compatible : Should be set to one of the following supported values: >>>>>>>> + - "samsung,exynos5250-usbdrd-phy" - for exynos5250 SoC, >>>>>>>> + - "samsung,exynos5420-usbdrd-phy" - for exynos5420 SoC. >>>>>>>> +- reg : Register offset and length of USB DRD PHY register set; >>>>>>>> +- clocks: Clock IDs array as required by the controller >>>>>>>> +- clock-names: names of clocks correseponding to IDs in the clock >>>>>>>> property; >>>>>>>> + Required clocks: >>>>>>>> + - phy: main PHY clock (same as USB DRD controller i.e. DWC3 IP >>>>>>>> clock), >>>>>>>> + used for register access. >>>>>>>> + - ref: PHY's reference clock (usually crystal clock), associated by >>>>>>>> + phy name, used to determine bit values for clock settings >>>>>>>> + register. >>>>>>>> + Additional clock required for Exynos5420: >>>>>>>> + - usb30_sclk_100m: Additional special clock used for PHY operation >>>>>>>> + depicted as 'sclk_usbphy30' in CMU of Exynos5420. >>>>>>>> +- samsung,syscon-phandle: phandle for syscon interface, which is used to >>>>>>>> + control pmu registers for power isolation. >>>>>>>> +- samsung,pmu-offset: phy power control register offset to >>>>>>>> pmu-system-controller >>>>>>>> + base. >>>>>>>> +- #phy-cells : from the generic PHY bindings, must be 1; >>>>>>>> + >>>>>>>> +For "samsung,exynos5250-usbdrd-phy" and "samsung,exynos5420-usbdrd-phy" >>>>>>>> +compatible PHYs, the second cell in the PHY specifier identifies the >>>>>>>> +PHY id, which is interpreted as follows: >>>>>>>> + 0 - UTMI+ type phy, >>>>>>>> + 1 - PIPE3 type phy, >>>>>>>> + >>>>>>>> +Example: >>>>>>>> + usb3_phy: usbphy@12100000 { >>>>>>>> + compatible = "samsung,exynos5250-usbdrd-phy"; >>>>>>>> + reg = <0x12100000 0x100>; >>>>>>>> + clocks = <&clock 286>, <&clock 1>; >>>>>>>> + clock-names = "phy", "usb3phy_refclk"; >>>>>>>> + samsung,syscon-phandle = <&pmu_syscon>; >>>>>>>> + samsung,pmu-offset = <0x704>; >>>>>>>> + #phy-cells = <1>; >>>>>>>> + }; >>>>>>>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig >>>>>>>> index 8d3c49c..d955a05 100644 >>>>>>>> --- a/drivers/phy/Kconfig >>>>>>>> +++ b/drivers/phy/Kconfig >>>>>>>> @@ -166,4 +166,15 @@ config PHY_XGENE >>>>>>>> help >>>>>>>> This option enables support for APM X-Gene SoC multi-purpose PHY. >>>>>>>> >>>>>>>> +config PHY_EXYNOS5_USBDRD >>>>>>>> + tristate "Exynos5 SoC series USB DRD PHY driver" >>>>>>>> + depends on ARCH_EXYNOS5 && OF >>>>>>>> + depends on HAS_IOMEM >>>>>>>> + select GENERIC_PHY >>>>>>>> + select MFD_SYSCON >>>>>>> >>>>>>> Lets try to avoid select in Kconfig. We've got enough problems with that. >>>>>> >>>>>> I hope you meant with "select MFD_SYSCON". >>>>>> We are referencing the syscon for accessing pmu reg, for which we need >>>>>> this config to be selected. >>>>>> Other Exynos phy drivers also need this config and for that they have >>>>>> selected this. >>>>>> >>>>>> Do you want me to do it any other way ? >>>>> >>>>> depends on is one option. >>>> >>>> Ok, i can see there are places where depends_on MFD_SYSCON is used. >>>> "drivers/gpu/drm/exynos/Kconfig:60" >>>> >>>> so, do you want me to fix at other places too ? >>>> >>>> But i also have a question here. >>>> MFD_SYSCON is a subsystem that's facilitating us in getting our work >>>> done here by giving an access to pmu_system_controller. >>>> So unless MFD_SYSCON is exposed, the phy driver will not be exposed to us. >>>> So is that valid enough really ? >>> >>> maybe in the Kconfig for MFD_SYSCON, we can select it if PHY_EXYNOS5_USBDRD is >>> enabled? >>> >>> config MFD_SYSCON >>> default y if PHY_EXYNOS5_USBDRD >> >> Yes, that seems to be one option. But we will end up adding this >> dependency for all the drivers which want to use syscon. >> >> Adding few people who worked on MFS_SYSCON, just to gather ideas. >> >> Re-quoting our problem here: >> "Inside our phy driver we are accessing power mgt unit registers, >> which we register using syscon in ut device tree. >> Now we don't want to select MFD_SYSCON from our phy driver, instead >> want to go 'depend_on' way." >> >> So one solution seems to be enabling MFD_SYSCON by default, if any of >> driver using syscon is enabled. >> Can we use some other way here ? > > This is an awful idea from maintainability perspective... This means that every > driver depending on MFD_SYSCON would have to add new "default y if" to > MFD_SYSCON Kconfig entry. Even with respect to readability, it is more logical > to have all dependencies of a driver listed in its Kconfig entry. > > Anyway, PHY_EXYNOS5_USBDRD can't work without MFD_SYSCON and somehow this needs > to be stated. I believe select is the right thing here and I'm not sure why it > could be a problem. The biggest reason for going this way is that users 'select' selects a module without caring for the dependencies and introduce compilation warnings. It should always be used with caution. 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/