Re: [PATCH/RFC] serial_core: Fix pm imbalance on unbind

From: Greg Kroah-Hartman
Date: Thu Mar 20 2014 - 17:12:38 EST

On Thu, Mar 20, 2014 at 11:23:00AM +0100, Geert Uytterhoeven wrote:
> Hi Greg,
> On Mon, Mar 10, 2014 at 8:54 PM, Geert Uytterhoeven
> <geert@xxxxxxxxxxxxxx> wrote:
> > From: Geert Uytterhoeven <geert+renesas@xxxxxxxxxxxxxx>
> >
> > When a serial port is closed, uart_close() takes care of shutting down the
> > hardware, and powering it down.
> >
> > When a serial port is unbound while in use, uart_close() bypasses all of
> > this, as this is supposed to be done through uart_hangup() (invoked via
> > tty_vhangup() in uart_remove_one_port()).
> >
> > However, uart_hangup() does not set the hardware's power state, leaving it
> > powered up. This may also lead to unbounded nesting counts in clock and
> > power management, depending on their internal implementation.
> >
> > Make sure to power down the port in uart_hangup(), except when the port is
> > used as a serial console. For serial consoles, this must be postponed until
> > after their deregistration in uart_remove_one_port() (symmetry with
> > registration in uart_configure_port(), invoked from uart_add_one_port()).
> >
> > After this, the module clock used by the sh-sci driver is disabled on
> > unbind while the serial port is in use.
> >
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxxxxxxx>
> I noticed you have applied all serial patches I've sent, except for this one.
> Is there any specific reason you skipped this one?

It was marked "RFC" so I didn't think it was to be applied...

If it's ready, please resend.


greg k-h
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