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    SubjectRe: [PATCH v2 4/6] ARM: firmware: add prepare_idle() operation
    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@nvidia.com>
    >>> ---
    >>> 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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