Re: [PATCH V4 1/5] phy: Add new Exynos5 USB 3.0 PHY driver

[Vivek Gautam]

On Mon, Apr 14, 2014 at 6:29 PM, Kishon Vijay Abraham I <kishon@xxxxxx> 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 <kishon@xxxxxx> 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 <gautam.vivek@xxxxxxxxxxx>
>>>> ---
>>>>  .../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 ?

>
> Thanks
> Kishon
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-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India
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