Re: [PATCH 0/2] Put OMAP2 SPI CS in unactive state when return from suspend

[Gregory CLEMENT <gclement00-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

2010/8/11 Kevin Hilman <khilman-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org>

> Gregory CLEMENT <gclement00-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:
>
> > We notice that when system wake up from OFF mode, then CS is in
> > unactive state until the first SPI transfert.
> > For our design it lead to some conflict on this I/O.
> > Unactive state for CS when there is no transfert shoudl be the correct
> > behaviour: this is the purpose of these patches.
>
> This approach handles an off-mode transition during suspend, but if
> off-mode is enabled, you can also have an off-mode transition during
> idle.
>
>
Well maybe I didn't use the correct words.
During the system life, I monitored the CS behaviour using a oscilloscope.
I also activate debug in omap2_mcspi, so I see when driver disable the
clocks and restore context when device is not used.
Each time the CS is in the correct state. It is only when there is a suspend
with the following configuration that on resume the CS is in wrong state( ie
activated)


echo 1 > /mnt/pm_debug/enable_off_mode
echo 0 > /mnt/pm_debug/core_pwrdm/suspend
echo 1 > /mnt/pm_debug/voltage_off_while_idle



> Since you didn't describe what the conflicts you're seeing are, I would
> assume that you'll have the same problems in idle as in suspend, and
> this series doesn't address the idle case.
>

I didn't see any problem in idle case, just when system resume from a
suspend to ram (echo mem > /sys/power/state)


>
> Kevin
>
>
>
> > Gregory CLEMENT (2):
> >   spi: Add hook on suspend/resume for spi master
> >   spi/omap2_mcspi: When SPI wake up from OFF mode, CS is in wrong
> >     state: force it to unactive state
> >
> >  drivers/spi/omap2_mcspi.c |   11 ++++++++++-
> >  drivers/spi/spi.c         |   15 ++++++++++++++-
> >  include/linux/spi/spi.h   |    4 +++-
> >  3 files changed, 27 insertions(+), 3 deletions(-)
> > --
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>



-- 
Gregory CLEMENT
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