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From: Baruch Siach <baruch@tkos.co.il>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Gregory Clement <gregory.clement@bootlin.com>,
	Jason Cooper <jason@lakedaemon.net>,
	linux-arm-kernel@lists.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH 2/2] arm64: dts: marvell: clearfog-gt-8k: set SFP power limit
Date: Sun, 19 May 2019 21:25:03 +0300	[thread overview]
Message-ID: <87pnoe2tfk.fsf@tarshish> (raw)
In-Reply-To: <20190519182053.anqoet5peeda7xtn@shell.armlinux.org.uk>

Hi Russell,

On Sun, May 19 2019, Russell King wrote:
> On Sun, May 19, 2019 at 12:21:06PM +0300, Baruch Siach wrote:
>> The Clearfog GT-8K board is capable of supplying power up to 2A to SFP
>> modules. Make that explicit in the device-tree. Without this property
>> current kernel does not allow SFP modules that require more than 1A.
>
> I do hope you're aware that current is not the same thing as power!
> You say above "2A" which is a current, but the maximum power figure
> below is "2W".  Given that modules are supplied with 3.3V, and
> Power = Voltage x Current, this really doesn't work out!
>
> Please can you correct both of your patches for accuracy in this
> regard, thanks.

My bad. I'll fix and resend.

Thanks for reviewing.

baruch

>> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
>> ---
>>  arch/arm64/boot/dts/marvell/armada-8040-clearfog-gt-8k.dts | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/arch/arm64/boot/dts/marvell/armada-8040-clearfog-gt-8k.dts b/arch/arm64/boot/dts/marvell/armada-8040-clearfog-gt-8k.dts
>> index 9143aa13ceb1..f275d9420d5b 100644
>> --- a/arch/arm64/boot/dts/marvell/armada-8040-clearfog-gt-8k.dts
>> +++ b/arch/arm64/boot/dts/marvell/armada-8040-clearfog-gt-8k.dts
>> @@ -63,6 +63,7 @@
>>  		tx-disable-gpio = <&cp1_gpio1 29 GPIO_ACTIVE_HIGH>;
>>  		pinctrl-names = "default";
>>  		pinctrl-0 = <&cp0_sfp_present_pins &cp1_sfp_tx_disable_pins>;
>> +		maximum-power-milliwatt = <2000>;
>>  	};
>>  
>>  	leds {

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -

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      reply	other threads:[~2019-05-19 18:25 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-19  9:21 [PATCH 1/2] arm64: dts: marvell: mcbin: set SFP power limit Baruch Siach
2019-05-19  9:21 ` [PATCH 2/2] arm64: dts: marvell: clearfog-gt-8k: " Baruch Siach
2019-05-19 18:20   ` Russell King - ARM Linux admin
2019-05-19 18:25     ` Baruch Siach [this message]

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