linux-kernel - Re: [PATCH v7 3/5] usb: dwc3: make usb2 phy utmi interface configurable in DT

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Date:	Mon, 25 Jul 2016 00:24:26 +0800
From:	"William.wu" <William.wu@...k-chips.com>
To:	Heiko Stübner <heiko@...ech.de>,
	Rob Herring <robh@...nel.org>, Felipe Balbi <balbi@...nel.org>
Cc:	gregkh@...uxfoundation.org, linux-rockchip@...ts.infradead.org,
	briannorris@...gle.com, dianders@...gle.com,
	kever.yang@...k-chips.com, huangtao@...k-chips.com,
	frank.wang@...k-chips.com, eddie.cai@...k-chips.com,
	John.Youn@...opsys.com, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, sergei.shtylyov@...entembedded.com,
	mark.rutland@....com, devicetree@...r.kernel.org
Subject: Re: [PATCH v7 3/5] usb: dwc3: make usb2 phy utmi interface
 configurable in DT

Dear Heiko,


On 2016/7/17 18:28, Heiko Stübner wrote:
> Am Samstag, 16. Juli 2016, 17:57:15 schrieb Rob Herring:
>> On Thu, Jul 14, 2016 at 04:59:20PM +0800, William Wu wrote:
>>> Add snps,phyif-utmi-width devicetree property to configure
>>> the UTMI+ PHY with an 8- or 16-bit interface. UTMI+ PHY
>>> interface is a hardware property, and it's platform dependent.
>>> Normally,the PHYIF can be configured during coreconsultant.
>>             ^
>> space
>>
>>> But for some specific USB cores(e.g. rk3399 SoC DWC3), the
>>> default PHYIF configuration value is fault, so we need to
>>> reconfigure it by software.
>>>
>>> And refer to the DWC3 databook, the GUSB2PHYCFG.USBTRDTIM
>>> must be set to the corresponding value according to the
>>> UTMI+ PHY interface.
>>>
>>> Signed-off-by: William Wu <william.wu@...k-chips.com>
>>> ---
>>> Changes in v7:
>>> - remove quirk and use only one property to configure utmi (Heiko, Rob
>>> Herring)
>>>
>>> Changes in v6:
>>> - use '-' instead of '_' in dts (Rob Herring)
>>>
>>> Changes in v5:
>>> - None
>>>
>>> Changes in v4:
>>> - rebase on top of balbi testing/next, remove pdata (balbi)
>>>
>>> Changes in v3:
>>> - None
>>>
>>> Changes in v2:
>>> - add a quirk for phyif_utmi (balbi)
>>>
>>>   Documentation/devicetree/bindings/usb/dwc3.txt |  3 +++
>>>   drivers/usb/dwc3/core.c                        | 25
>>>   +++++++++++++++++++++++++ drivers/usb/dwc3/core.h
>>>   | 10 ++++++++++
>>>   3 files changed, 38 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt
>>> b/Documentation/devicetree/bindings/usb/dwc3.txt index 020b0e9..00cc541
>>> 100644
>>> --- a/Documentation/devicetree/bindings/usb/dwc3.txt
>>> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt
>>>
>>> @@ -47,6 +47,9 @@ Optional properties:
>>>    - snps,hird-threshold: HIRD threshold
>>>    - snps,hsphy_interface: High-Speed PHY interface selection between
>>>    "utmi" for>
>>>      UTMI+ and "ulpi" for ULPI when the DWC_USB3_HSPHY_INTERFACE has value
>>>      3.
>>>
>>> + - snps,phyif-utmi-width: the value to configure the core to support a
>>> UTMI+ PHY +			with an 8- or 16-bit interface. Value 8 select 8-bit
>>> +			interface, value 16 select 16-bit interface.
>> Is 'phy_type = "utmi_wide"' not the same as 16-bit width?
>>
>> Again, I think this should be common.
> after knowing that I need to look for that "utmi_wide", I think I'd agree.
>
> I found mention of that in usb/ci-hdrc-usb2.txt and usb/fsl-usb.txt and from
> the coresponding code, I can see that they really mean the 16bit interface,
> the Rockchip TRM as well as the spec [0] seems to call it UTMI+ but really
> looks the same as utmi_wide.
>
> Interestingly, there is already generic code in drivers/usb/phy/of.c so that
> property should probably move to devicetree/bindings/usb/generic.txt
> as well.
>
>
> Heiko
>
> [0] http://cache.nxp.com/files/corporate/doc/support_info/UTMI-PLUS-SPECIFICATION.pdf

Thank you very much for your kindly help and helpful suggestion.:-D
I quite agree with you about use ‘phy_type’ to config UTMI+ interface 
for DWC3 controller, and add the ‘phy_type’ property to 
devicetree/bindings/usb/generic.txt.

So I shouldn't add a new dts property ‘snps,phyif-utmi-width’ here， and 
just use ‘phy_type’is enough.

BTW, I think rk3399 UTMI+ isn't the same as ‘utmi_wide’. Because UTMI+ 
support both 8-bit data interface and 16-bit data interface, but refer 
to code in drivers/usb/phy/of.c and related driver，‘phy_type = 
"utmi_wide"’means 16-bits, 'phy_type = utmi' means 8-bits.

Dear Felipe， how about your opinion about add ‘phy_type’ to config UTMI+ 
interface?

Best Regards
        William wu
>
>
>
>