linux-kernel - Re: [PATCH 1/5] drivers: usb: phy: add a new driver for omap usb2 phy

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Date:	Fri, 28 Sep 2012 08:12:04 -0700
From:	"Cousson, Benoit" <b-cousson@...com>
To:	"ABRAHAM, KISHON VIJAY" <kishon@...com>
CC:	Rob Herring <robherring2@...il.com>, <grant.likely@...retlab.ca>,
	<rob@...dley.net>, <tony@...mide.com>, <linux@....linux.org.uk>,
	<balbi@...com>, <gregkh@...uxfoundation.org>,
	<devicetree-discuss@...ts.ozlabs.org>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 1/5] drivers: usb: phy: add a new driver for omap usb2
 phy

On 9/28/2012 3:07 AM, ABRAHAM, KISHON VIJAY wrote:
> Hi,
>
> On Fri, Sep 28, 2012 at 4:18 AM, Cousson, Benoit <b-cousson@...com> wrote:
>> On 9/27/2012 7:24 AM, Rob Herring wrote:
>>>
>>> On 09/25/2012 05:06 AM, ABRAHAM, KISHON VIJAY wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Mon, Sep 24, 2012 at 6:45 PM, Rob Herring <robherring2@...il.com>
>>>> wrote:
>>>>>
>>>>> On 09/06/2012 09:57 AM, Kishon Vijay Abraham I wrote:
>>>>>>
>>>>>> All phy related programming like enabling/disabling the clocks,
>>>>>> powering
>>>>>> on/off the phy is taken care of by this driver. It is also used for OTG
>>>>>> related functionality like srp.
>>>>>>
>>>>>> This also includes device tree support for usb2 phy driver and
>>>>>> the documentation with device tree binding information is updated.
>>>>>>
>>>>>> Currently writing to control module register is taken care in this
>>>>>> driver which will be removed once the control module driver is in
>>>>>> place.
>>>>>>
>>>>>> Cc: Felipe Balbi <balbi@...com>
>>>>>> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
>>>>>> ---
>>>>>>    Documentation/devicetree/bindings/usb/usb-phy.txt |   17 ++
>>>>>>    drivers/usb/phy/Kconfig                           |    9 +
>>>>>>    drivers/usb/phy/Makefile                          |    1 +
>>>>>>    drivers/usb/phy/omap-usb2.c                       |  271
>>>>>> +++++++++++++++++++++
>>>>>>    include/linux/usb/omap_usb.h                      |   46 ++++
>>>>>>    include/linux/usb/phy_companion.h                 |   34 +++
>>>>>>    6 files changed, 378 insertions(+)
>>>>>>    create mode 100644 Documentation/devicetree/bindings/usb/usb-phy.txt
>>>>>>    create mode 100644 drivers/usb/phy/omap-usb2.c
>>>>>>    create mode 100644 include/linux/usb/omap_usb.h
>>>>>>    create mode 100644 include/linux/usb/phy_companion.h
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/usb/usb-phy.txt
>>>>>> b/Documentation/devicetree/bindings/usb/usb-phy.txt
>>>>>> new file mode 100644
>>>>>> index 0000000..80d4148
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/usb/usb-phy.txt
>>>>>
>>>>>
>>>>> This is a very generic name...
>>>>>
>>>>>> @@ -0,0 +1,17 @@
>>>>>> +USB PHY
>>>>>> +
>>>>>> +OMAP USB2 PHY
>>>>>> +
>>>>>> +Required properties:
>>>>>> + - compatible: Should be "ti,omap-usb2"
>>>>>
>>>>>
>>>>> ...for a specific phy. However, I do think a generic binding to describe
>>>>> host ctrlr to phy connections is needed.
>>>>>
>>>>>> + - reg : Address and length of the register set for the device. Also
>>>>>> +add the address of control module dev conf register until a driver for
>>>>>> +control module is added
>>>>>
>>>>>
>>>>> The dts should describe the h/w, not what you need for the current
>>>>> driver. The 2nd reg field does not belong here.
>>>>
>>>>
>>>> Indeed. This was discussed and agreed upon as a interim solution till
>>>> we have a control module driver in place to write to the control
>>>> module register.
>>>
>>>
>>> Discussed where and agreed by who? I for one do not agree.
>>
>>
>> Yeah, what was tolerated was the addition of that address inside hwmod data,
>> but I do agree that it should not go into DTS.
>
> So how can we handle reg writes to control module until we have a
> control module driver. usb2 phy does not have a hwmod data for itself.
> Do you think we should add a new hwmod data for usb2 phy and use this
> in the usb2phy data node in the dts file?

Now, I'm confused... didn't you already do that? What was the hwmod you 
added?

Maybe it is time to write your own control module driver now.

Talking with Tony on that, there is no need for a common control driver, 
it is up to each individual control driver to handle their own register 
space. It means that you should probably just add a simple driver to 
access these region.

Regards,
Benoit

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