Re: [PATCH v3 3/4] arm64: dts: apple: t8103: Add i2c nodes

[Hector Martin "marcan"]

On 2021年11月26日 0:50:28 JST, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>On Wed, Nov 24, 2021 at 6:42 AM Hector Martin <marcan@xxxxxxxxx> wrote:
>
>> Pulling down an I2C bus between transactions is not legal; the idle
>> state has to be high.
>
>Oh right.
>
>> Apple are actually not very good at configuring GPIOs for power saving;
>> e.g. the I/Os for that unused i2c bus still have their input buffers
>> turned on, which is a waste of power. If they wanted to save the
>> smallest drop of power they'd turn that off. But the effect of this is
>> so trivial it probably makes no difference in the context of a laptop,
>> nevermind a desktop like the Mac Mini.
>
>Hm that's true. The saying is that 99% is the backlight, the remaining 1% isn't
>so significant after that.

>From watching a USB power meter plugged into the MacBook Air, I can say the backlight is about 70% :-)

Then again, the new MBPs have LED matrix backlit screens... so suddenly dark themes are more efficient again! I should measure that one, see how much power changing themes saves.

-- 
Hector Martin "marcan" (marcan@xxxxxxxxx)
Public key: https://mrcn.st/pub