linux-kernel - Re: [PATCH v2 1/4] ARM: dts: omap4-panda: Add USB Host support

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Message-ID: <51C2EC5F.8050703@ti.com>
Date:	Thu, 20 Jun 2013 14:49:51 +0300
From:	Roger Quadros <rogerq@...com>
To:	Benoit Cousson <b-cousson@...com>
CC:	<florian.vaussard@...l.ch>, <devicetree-discuss@...ts.ozlabs.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 1/4] ARM: dts: omap4-panda: Add USB Host support

On 06/20/2013 01:40 AM, Benoit Cousson wrote:
> On 06/19/2013 09:05 AM, Roger Quadros wrote:
>> On 06/19/2013 03:23 PM, Benoit Cousson wrote:
>>> On 06/19/2013 07:05 AM, Florian Vaussard wrote:
>>>> Hello,
>>>>
>>>> On 06/19/2013 01:03 PM, Roger Quadros wrote:
>>>>> On 06/19/2013 01:10 PM, Benoit Cousson wrote:
>>>>>> On 06/19/2013 02:46 AM, Tony Lindgren wrote:
>>>>>>> * Roger Quadros <rogerq@...com> [130619 00:42]:
>>>>>>>> Hi Benoit,
>>>>>>>>
>>>>>>>> On 06/19/2013 04:17 AM, Benoit Cousson wrote:
>>>>>>>>> Hi Roger,
>>>>>>>>>
>>>>>>>>> On 06/18/2013 11:04 AM, Roger Quadros wrote:
>>>>>>>>>> Provide the RESET and Power regulators for the USB PHY,
>>>>>>>>>> the USB Host port mode and the PHY device.
>>>>>>>>>>
>>>>>>>>>> Also provide pin multiplexer information for the USB host
>>>>>>>>>> pins.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Roger Quadros <rogerq@...com>
>>>>>>>>>> ---
>>>>>>>>>>      arch/arm/boot/dts/omap4-panda-common.dtsi |   62
>>>>>>>>>> +++++++++++++++++++++++++++++
>>>>>>>>>>      1 files changed, 62 insertions(+), 0 deletions(-)
>>>>>>>>>>
>>>>>>>>>> diff --git a/arch/arm/boot/dts/omap4-panda-common.dtsi
>>>>>>>>>> b/arch/arm/boot/dts/omap4-panda-common.dtsi
>>>>>>>>>> index 00cbaa5..7a21e8e 100644
>>>>>>>>>> --- a/arch/arm/boot/dts/omap4-panda-common.dtsi
>>>>>>>>>> +++ b/arch/arm/boot/dts/omap4-panda-common.dtsi
>>>>>>>>>> @@ -59,6 +59,42 @@
>>>>>>>>>>                  "AFML", "Line In",
>>>>>>>>>>                  "AFMR", "Line In";
>>>>>>>>>>          };
>>>>>>>>>> +
>>>>>>>>>> +    /* HS USB Port 1 RESET */
>>>>>>>>>> +    hsusb1_reset: hsusb1_reset_reg {
>>>>>>>>>> +        compatible = "regulator-fixed";
>>>>>>>>>> +        regulator-name = "hsusb1_reset";
>>>>>>>>>> +        regulator-min-microvolt = <3300000>;
>>>>>>>>>> +        regulator-max-microvolt = <3300000>;
>>>>>>>>>> +        gpio = <&gpio2 30 0>;    /* gpio_62 */
>>>>>>>>>> +        startup-delay-us = <70000>;
>>>>>>>>>> +        enable-active-high;
>>>>>>>>>> +    };
>>>>>>>>>
>>>>>>>>> Is this really a regulator? Or just a GPIO line used to reset the
>>>>>>>>> USB PHY?
>>>>>>>>
>>>>>>>> It is in fact a GPIO line used as reset.
>>>>>>>>>
>>>>>>>>> If this is the case, I don't think it should be represented as a
>>>>>>>>> regulator.
>>>>>>>>
>>>>>>>> Why not? I think it fits very well in the regulator device model.
>>>>>>
>>>>>> I'm not sure fitting very well is the correct term.
>>>>>> It works, for sure, but it is no different than when we were trying
>>>>>> to abuse the regulator fmwk to enable the 32k clock in phoenix.
>>>>>> It is just a hack.
>>>>>>
>>>>>
>>>>> The only difference is there is a dedicated framework for clocks.
>>>>> Since there is nothing specific to
>>>>> handle reset lines it is left to the driver writer how he wants to
>>>>> manage it.
>>>>>
>>>>
>>>> There is a proposed binding for gpio-controlled reset lines, but it is
>>>> not yet merged [1].
>>>> I guess it can fit most usage patterns, and it can be an interesting
>>>> move in the future.
>>>
>>> I'm glad to see that I was not the only one thinking that the regulator was not the right fmwk to do that :-)
>>>
>>> Thanks for the pointer Florian.
>>
>> Thanks again Florian.
>>>
>>> I guess that series should be merged for 3.11? Based on the thread, it should to through arm-soc.
>>>
>>> Roger,
>>>
>>> It might be tricky to have dependency on that series, but if this is possible, you should try. Otherwise, just keep the existing one, adding that a new solution will be available soon as a disclaimer.
>>>
>>
>> I will rework the PHY driver to use the new gpio-reset driver. But for 3.11 let's proceed the way it is.
>> I'll resend this one with a disclaimer.
> 
> OK, I've just done it myself while applying your series.
>

Great !! Thanks.

There is a similar patch for beagle-xm. But I will resend it to you with the disclaimer.

cheers,
-roger
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