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

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Message-ID: <51C1F5D6.3040304@ti.com>
Date:	Wed, 19 Jun 2013 13:17:58 -0500
From:	Benoit Cousson <b-cousson@...com>
To:	Roger Quadros <rogerq@...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 06/19/2013 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, sounds good.

Thanks,
Benoit

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