linux-kernel - Re: [PATCH v2 1/6] ARM: dts: dra7-evm: Make VDDA_1V8

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Date:	Mon, 7 Jul 2014 11:34:18 +0300
From:	Roger Quadros <rogerq@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	<kishon@...com>, <balbi@...com>, <nsekhar@...com>, <nm@...com>,
	<george.cherian@...com>, <sergei.shtylyov@...entembedded.com>,
	<linux-omap@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Rajendra Nayak <rnayak@...com>,
	Tero Kristo <t-kristo@...com>
Subject: Re: [PATCH v2 1/6] ARM: dts: dra7-evm: Make VDDA_1V8_PHY supply always
 on

Hi Tony,

On 07/07/2014 11:29 AM, Tony Lindgren wrote:
> * Roger Quadros <rogerq@...com> [140704 02:57]:
>> After clarification from the hardware team it was found that
>> this 1.8V PHY supply can't be switched OFF when SoC is Active.
>>
>> Since the PHY IPs don't contain isolation logic built in the design to
>> allow the power rail to be switched off, there is a very high risk
>> of IP reliability and additional leakage paths which can result in
>> additional power consumption.
>>
>> The only scenario where this rail can be switched off is part of Power on
>> reset sequencing, but it needs to be kept always-on during operation.
>>
>> This patch is required for proper functionality of USB, SATA
>> and PCIe on DRA7-evm.
>>
>> CC: Rajendra Nayak <rnayak@...com>
>> CC: Tero Kristo <t-kristo@...com>
>> Signed-off-by: Roger Quadros <rogerq@...com>
> 
> Best that you queue this with the series:

This patch doesn't have any dependency with the others and we're not even sure if
this series will hit 3.16.

But this 1V8 regulator _is_ required for normal operation of the SoC, whether the
PHYs are in use or not.

Can you please queue just this patch for SoC fixes for 3.16? Thanks.

cheers,
-roger

> 
> Acked-by: Tony Lindgren <tony@...mide.com>
> 
>> ---
>>  arch/arm/boot/dts/dra7-evm.dts | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm/boot/dts/dra7-evm.dts b/arch/arm/boot/dts/dra7-evm.dts
>> index 4adc280..8308954 100644
>> --- a/arch/arm/boot/dts/dra7-evm.dts
>> +++ b/arch/arm/boot/dts/dra7-evm.dts
>> @@ -240,6 +240,7 @@
>>  					regulator-name = "ldo3";
>>  					regulator-min-microvolt = <1800000>;
>>  					regulator-max-microvolt = <1800000>;
>> +					regulator-always-on;
>>  					regulator-boot-on;
>>  				};
>>  
>> -- 
>> 1.8.3.2
>>

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