Re: [PATCH 1/3] x86: ce4100: implement pm_poweroff

From: Ingo Molnar
Date: Fri Oct 26 2012 - 05:30:23 EST



* Florian Fainelli <ffainelli@xxxxxxxxxx> wrote:

> The CE4100 platform is currently missing a proper pm_poweroff implementation
> leading to poweroff making the CPU spin forever and the CE4100 platform does
> not enter a low-power mode where the external Power Management Unit can
> properly power off the system. Power off on this platform is implemented pretty
> much like reboot, by writing to the SoC built-in 8051 microcontroller mapped at
> I/O port 0xcf9, the value 0x4.
>
> Signed-off-by: Florian Fainelli <ffainelli@xxxxxxxxxx>
> ---
> arch/x86/platform/ce4100/ce4100.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/platform/ce4100/ce4100.c b/arch/x86/platform/ce4100/ce4100.c
> index 4c61b52..74f8774 100644
> --- a/arch/x86/platform/ce4100/ce4100.c
> +++ b/arch/x86/platform/ce4100/ce4100.c
> @@ -27,6 +27,11 @@ static int ce4100_i8042_detect(void)
> return 0;
> }
>
> +static void ce4100_power_off(void)
> +{
> + outb(0x4, 0xcf9);

Would be nice to precede this function with something like:

/*
* Power off on this platform is implemented pretty
* much like reboot, by writing to the SoC built-in
* 8051 microcontroller mapped at I/O port 0xcf9,
* the magic value 0x4:
*/
static void ce4100_power_off(void)
{
outb(0x4, 0xcf9);
...

As arguably such comments are even more useful in the code than
in a changelog.

Thanks,

Ingo
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