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

[Vivek Gautam]

Hi,


On Mon, Apr 14, 2014 at 7:14 PM, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote:
> On 14.04.2014 15:05, Kishon Vijay Abraham I wrote:
>>
>>
>>
>> On Monday 14 April 2014 05:35 PM, Vivek Gautam wrote:
>>>
>>> Hi Kishon,
>>>
>>>
>>> On Mon, Apr 14, 2014 at 5:24 PM, Kishon Vijay Abraham I <kishon@xxxxxx>
>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Wednesday 09 April 2014 04:36 PM, Tomasz Figa wrote:
>>>>>
>>>>> Hi Vivek,
>>>>>
>>>>> Please see my comments inline.
>>>>>
>>>>> On 08.04.2014 16:36, 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
>>>>>
>>>>>
>>>>> [snip]
>>>>>
>>>>>> +    Additional clock required for Exynos5420:
>>>>>> +    - usb30_sclk_100m: Additional special clock used for PHY
>>>>>> operation
>>>>>> +               depicted as 'sclk_usbphy30' in CMU of Exynos5420.
>>>>>
>>>>>
>>>>> Are you sure this isn't simply a gate for the ref clock, as it can be
>>>>> found on
>>>>> another SoC that is not upstream yet? I don't have documentation for
>>>>> Exynos
>>>>> 5420 so I can't tell, but I'd like to ask you to recheck this.
>>>>>
>>>>>> +- 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";
>>>>>
>>>>>
>>>>> Binding description above doesn't mention "usb3phy_refclk" entry.
>>>>>
>>>>>> +        samsung,syscon-phandle = <&pmu_syscon>;
>>>>>> +        samsung,pmu-offset = <0x704>;
>>>>>> +        #phy-cells = <1>;
>>>>>> +    };
>>>>>
>>>>>
>>>>> [snip]
>>>>>
>>>>>> diff --git a/drivers/phy/phy-exynos5-usbdrd.c
>>>>>> b/drivers/phy/phy-exynos5-usbdrd.c
>>>>>> new file mode 100644
>>>>>> index 0000000..ff54a7c
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/phy/phy-exynos5-usbdrd.c
>>>>>
>>>>>
>>>>> [snip]
>>>>>
>>>>>> +static int exynos5_usbdrd_phy_probe(struct platform_device *pdev)
>>>>>> +{
>>>>>> +    struct device *dev = &pdev->dev;
>>>>>> +    struct device_node *node = dev->of_node;
>>>>>> +    struct exynos5_usbdrd_phy *phy_drd;
>>>>>> +    struct phy_provider *phy_provider;
>>>>>> +    struct resource *res;
>>>>>> +    const struct of_device_id *match;
>>>>>> +    const struct exynos5_usbdrd_phy_drvdata *drv_data;
>>>>>> +    struct regmap *reg_pmu;
>>>>>> +    u32 pmu_offset;
>>>>>> +    int i;
>>>>>> +
>>>>>> +    /*
>>>>>> +     * Exynos systems are completely DT enabled,
>>>>>> +     * so lets not have any platform data support for this driver.
>>>>>> +     */
>>>>>> +    if (!node) {
>>>>>> +        dev_err(dev, "no device node found\n");
>>>>>
>>>>>
>>>>> This error message is not very meaningful. I'd rather use something
>>>>> like "This
>>>>> driver can be only instantiated using Device Tree".
>>>>
>>>>
>>>> how about just adding depend_on OF in Kconfig?
>>>
>>>
>>> Already added a depend on 'OF'. Copying below the part of Kconfig in this
>>> patch.
>>
>>
>> Alright.. Do we need the check then? If config_OF is enabled devices will
>> be
>> created using device tree no?
>
>
> Not necessarily. Enabling support for OF doesn't mean that it is the only
> boot method that can be used. Legacy board files may be still available. I'm
> not sure why someone would try to instantiate this driver from them, though.

True, we don't have a scope of instantiating this driver using old
platform device and
old legacy board files.
So we don't need this check then, right ?


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