Re: [x86-power-control]: press the power button for a long time that can't force turn off system power

[Andrew Jeffery]

Hi Chris,

On Tue, 17 Aug 2021, at 20:47, Chris Chen (TPI) wrote:
> Hi Andrew,
> 
> That means I'm able to choose one of following 2 options to achieve 
> pass-through behavior when I using x86-power-control package, is my 
> understanding correct?
> 
> 1. Add code to re-enable GPIOP0 and GPIOP1 into a pass-through function 
> after they are requested as a GPIO function in the x86-power-control 
> package. (Or maybe to create a script with "devmem > 0x1e6e24BC 32 
> 0x0F000000" command that will be run automatically after system up to 
> change register directly.)

This is a hack and should be a last resort. Even then I'd avoid it.

Certainly you should avoid shipping with /dev/mem enabled.

> 
> 2. Modify pinctrl in Kernel that will not disable GPIOP0 and GPIOP1's 
> pass-through function if they already are configured as a pass-through 
> when they are requesting as a GPIO function.

Perhaps, though maybe you should follow up on whether you can drive 
GPIOP1 when it's in pass-through mode. My recollection is you cannot, 
at least for the AST2500 and earlier, in which case both P0 and P1 are 
effectively inputs for the purpose of the GPIO controller despite P1 
being a physical output. This behaviour is probably more confusing than 
it is helpful.

There's also option 3 which is to emulate the pass-through in software, 
as I outlined in my previous email.

Hope that helps,

Andrew