Arnd Bergmann <a...@arndb.de> writes:
>> It looks to me the powermode should be initialized once and for all in the
>> machine init code. So unless I've overseen something, I'll keep Thierry's
>> patch.
>
> Ah, sorry. I should have looked at the link you sent.
>
> Thierry's patch indeed looks much nicer if that works, but I'm not entirely
> sure if it is safe or not. Only two other pxa27x machines set the
> PWRMODE_DEEPSLEEP
> flag, so it looks like there is a reason for some machines not to set it.
Yes, the reason is that the default is set PWRMODE_SLEEP as set in pxa27x.c
This is the only choice for suspend to RAM, as it :
- disables a lot of power islands
- and yet keeps Vcc_Mem powered for suspend to RAM
> The z2 in particular never did, except in the powerdown handler. So if it
> is unable to wake up reliably from DEEPSLEEP, that may be a reason to use
> that flag only in the poweroff function but not during normal operation.
My first thought was :
This flag's only use is for Suspend to RAM. There might be special
wirings where the voltage to the RAM is provided out of SYS_EN pin
control, and therefore PWRMODE_DEEPSLEEP is possible. But the most
common pattern would be a PMIC, providing voltage to the DRAM through
Vcc_Mem.
But having a closer look, you're right, I have misunderstood the way z2 poweroff
was designed. The setting of poweroff to PWRMODE_DEEPSLEEP +
pxa27x_cpu_pm_enter() is a whole, it is the closest to a platform halt where no
external chip handles the poweroff phase, and memory is shutdown in deep sleep.
Therefore I'll drop Thierry's patch (which would actually break suspend to RAM I
think) and take yours.
Cheers.
--
Robert
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
