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

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Message-ID: <534BDD17.60003@ti.com>
Date:	Mon, 14 Apr 2014 18:35:27 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Vivek Gautam <gautam.vivek@...sung.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



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@...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.

Alright.. Do we need the check then? If config_OF is enabled devices will be
created using device tree no?

Thanks
Kishon
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