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

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Message-ID: <CAFp+6iGxhfgZRPysMuj5nALEQBbFXnAXhtDPpbf3P42LDHqFxg@mail.gmail.com>
Date:	Mon, 14 Apr 2014 17:35:43 +0530
From:	Vivek Gautam <gautam.vivek@...sung.com>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	Tomasz Figa <t.figa@...sung.com>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linux-doc@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Kamil Debski <k.debski@...sung.com>,
	Jingoo Han <jg1.han@...sung.com>,
	Sylwester Nawrocki <sylvester.nawrocki@...il.com>
Subject: Re: [PATCH V4 1/5] phy: Add new Exynos5 USB 3.0 PHY driver

Hi Kishon,


On Mon, Apr 14, 2014 at 5:24 PM, Kishon Vijay Abraham I <kishon@...com> 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@...sung.com>
>>> ---
>>>   .../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@...00000 {
>>> +        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.

  config PHY_EXYNOS5_USBDRD
         tristate "Exynos5 SoC series USB DRD PHY driver"
         depends on ARCH_EXYNOS5 && OF
         depends on HAS_IOMEM
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