Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755245AbaDNNuD (ORCPT ); Mon, 14 Apr 2014 09:50:03 -0400 Received: from mail-ee0-f43.google.com ([74.125.83.43]:64442 "EHLO mail-ee0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753711AbaDNNt4 (ORCPT ); Mon, 14 Apr 2014 09:49:56 -0400 Message-ID: <534BE77E.5090902@gmail.com> Date: Mon, 14 Apr 2014 15:49:50 +0200 From: Tomasz Figa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Vivek Gautam , Kishon Vijay Abraham I , Mark Brown , Stephen Warren , dong.aisheng@linaro.org, sameo@linux.intel.com 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" , linux-doc@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> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 wouldn't have to care about internal dependencies, instead they would simply enable drivers for their hardware. Best regards, Tomasz -- 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/