On Sun, Oct 31, 2010 at 11:56 PM, Daniel Clark <[email protected]> wrote:
>> 2. Do hibernation
>>
>> $ echo disk > /sys/power/state
>
> Is the thing with the disk hibernation not being that useful due to a fan
> staying on (in a way that would need to be fixed in hardware) somehow fixed
> now, either by a clever software hack or a hardware change in more recent
> production yeeloongs?

For the FAN problem, do you mean "suspend to RAM"(echo mem > /sys/power/state)?

Hibernation(Suspend to disk, "echo disk > /sys/power/state") doesn't
have this problem for it will turn off the whole machine.

"Suspend to RAM" will not turn off the FAN for currently, "Suspend to
RAM" doesn't function completely, which means even if we suspend the
system to RAM, some of the external devices can not be turned off(for
hardware problems, no hardware interfaces to turn them off),
therefore, we still need the FAN to ensure the temperature is not too
high, otherwise, you may potentially get a broken machine.

Although we can turn off the FAN via the software interface(with the
help of the yeeloong_laptop module):

// Enable the manual mode of the Fan: 0 full speed; 1 manual; 2 auto(default)
echo 1 > /sys/devices/virtual/hwmon/hwmon0/pwm1_enable
// Change the RPM: 0(turn off), 1, 2, 3(default)
echo 1 > /sys/devices/virtual/hwmon/hwmon0/pwm1

But to consider the hardware safety, we'd better keep the FAN works in
auto mode: in this mode, it can adjust its speed automatically based
on the external temperature.

So, I think hibernation is better than "Suspend to RAM" although we
may need more time to do it(several seconds). But if you don't care
for the power consumption, please use "Suspend to RAM" instead for it
also save more than 50% power for you, "Suspend to RAM" only need
about 5 w and the default system need about 12.21 V * 0.93 A = 11.0838
W (the data is collected by the "sensors" command).

Regards,
Wu Zhangjin

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