From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
balbi@ti.com, linux-omap@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, tony@atomide.com,
mika.westerberg@linux.intel.com
Subject: Re: [RFC PATCH 3/4] tty: serial: 8250 core: add runtime pm
Date: Mon, 7 Jul 2014 14:20:56 +0100 [thread overview]
Message-ID: <20140707142056.46f61cf9@alan.etchedpixels.co.uk> (raw)
In-Reply-To: <1404491651-1388-3-git-send-email-bigeasy@linutronix.de>
On Fri, 4 Jul 2014 18:34:10 +0200
Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> While comparing the OMAP-serial and the 8250 part of this I noticed that
> the the latter does not use runtime-pm.
Yes it does, but 8250 parts (generally - omap presumably is special
here ?) need to be powered on to transmit/receive not just for register
access. The core uart layer implements a "pm" operation for this.
As 8250_dw uses runtime pm to implement the pm operation it's not as
simple as assumign it won't get triggered.
I *think* this is ok because the designware and other cases would take a
reference on open and drop it on close, so avoiding any confusion, but
for the register accesses on a closed port it would benefit from a
further double check with Mika especially as the suspend/resume on the
LPSS block on some Intel devices is a little bit too "interesting" for
comfort.
Otherwise however I think this is good.
Alan
next prev parent reply other threads:[~2014-07-07 13:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-04 16:34 [RFC PATCH 1/4] tty: serial: 8250 core: provide a function to export uart_8250_port Sebastian Andrzej Siewior
2014-07-04 16:34 ` [RFC PATCH 2/4] tty: serial: 8250 core: allow to overwrite & export serial8250_startup() Sebastian Andrzej Siewior
2014-07-07 13:09 ` One Thousand Gnomes
2014-07-09 17:39 ` Sebastian Andrzej Siewior
2014-07-04 16:34 ` [RFC PATCH 3/4] tty: serial: 8250 core: add runtime pm Sebastian Andrzej Siewior
2014-07-07 13:20 ` One Thousand Gnomes [this message]
2014-07-09 11:17 ` Tony Lindgren
2014-07-09 11:35 ` Sebastian Andrzej Siewior
2014-07-09 11:48 ` Tony Lindgren
2014-07-09 12:42 ` Sebastian Andrzej Siewior
2014-07-09 15:12 ` Tony Lindgren
2014-07-09 16:32 ` Sebastian Andrzej Siewior
2014-07-10 6:43 ` Tony Lindgren
2014-07-04 16:34 ` [RFC PATCH 4/4] tty: serial: Add 8250-core based omap driver v2 Sebastian Andrzej Siewior
2014-07-07 13:09 ` [RFC PATCH 1/4] tty: serial: 8250 core: provide a function to export uart_8250_port One Thousand Gnomes
2014-07-09 17:23 ` Sebastian Andrzej Siewior
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