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    SubjectRe: [RFC/PATCH 10/13] serial: omap: stick to put_autosuspend
    On Tue, Aug 21, 2012 at 04:12:11PM +0530, Shilimkar, Santosh wrote:
    > On Tue, Aug 21, 2012 at 2:45 PM, Felipe Balbi <balbi@ti.com> wrote:
    > > Everytime we're done using our TTY, we want
    > > the pm timer to be reinitilized. By sticking
    > > to pm_runtime_pm_autosuspend() we make sure
    > > that this will always be the case.
    > >
    > > Signed-off-by: Felipe Balbi <balbi@ti.com>
    > > ---
    > > drivers/tty/serial/omap-serial.c | 33 ++++++++++++++++++++++-----------
    > > 1 file changed, 22 insertions(+), 11 deletions(-)
    > >
    > > diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
    > > index 6ea24c5..458d77c 100644
    > > --- a/drivers/tty/serial/omap-serial.c
    > > +++ b/drivers/tty/serial/omap-serial.c
    > > @@ -164,7 +164,8 @@ static void serial_omap_enable_ms(struct uart_port *port)
    > > pm_runtime_get_sync(up->dev);
    > > up->ier |= UART_IER_MSI;
    > > serial_out(up, UART_IER, up->ier);
    > > - pm_runtime_put(up->dev);
    > > + pm_runtime_mark_last_busy(up->dev);
    > > + pm_runtime_put_autosuspend(up->dev);
    > > }
    > >
    > Can you please expand the change-log a bit ?
    > Didn't follow the time re-init part completely.

    It's really just a micro-optimization. The thing is:

    if I call pm_runtime_put(), I will not reinitialize the pm timer to
    whatever timeout value I used. This means that pm_runtime_put() could
    actually execute right away (if timer was about to expire when I called
    pm_runtime_put()). While this wouldn't cause any issues, it's better to
    reinitialize the timer and make sure if there's another
    read/write/set_termios/whatever coming right after this, UART is still
    powered up.

    I mean, it's really just trying to avoid context save & restore when
    UART is still under heavy usage.

    Does it make sense ?

    --
    balbi
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