Re: [PATCH v2 4/6] ARM: firmware: add prepare_idle() operation

[Tomasz Figa]

On 14.02.2014 06:16, Alexandre Courbot wrote:
> On 02/13/2014 08:01 PM, Tomasz Figa wrote:
> > Hi Alexandre,
> >
> > On 07.02.2014 05:35, Alexandre Courbot wrote:
> > > Some firmwares do not put the CPU into idle mode themselves, but still
> > > need to be informed that the CPU is about to enter idle mode before this
> > > happens. Add a prepare_idle() operation to the firmware_ops structure to
> > > handle such cases.
> > >
> > > Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
> > > ---
> > >    arch/arm/include/asm/firmware.h | 4 ++++
> > >    1 file changed, 4 insertions(+)
> >
> > I wonder if .do_idle() couldn't simply return an appropriate error code
> > to let the upper layer know that it should proceed with normal CPU idle
> > activation, while still letting the firmware know that the CPU is going
> > to idle.
>
> In our particular case I agree it would be enough to use do_idle() to
> let the firmware know about the operation and have it return -ENOSYS so
> the kernel actually performs it. I'm afraid this might not fulfill all
> needs though (e.g. one can imagine a firmware where the OS needs to take
> action between the notification and the actual shutdown), and as Stephen
> pointed out that would make the name of the function ambiguous at best.
> I'd rather keep it the current way for clarity.

OK. I'm not strongly against this, just wanted some more thought on 
this, so please move on.

Best regards,
Tomasz
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