Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755156Ab3DWFOu (ORCPT ); Tue, 23 Apr 2013 01:14:50 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:46961 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754721Ab3DWFOt (ORCPT ); Tue, 23 Apr 2013 01:14:49 -0400 Message-ID: <517618BB.7040603@ti.com> Date: Tue, 23 Apr 2013 10:44:35 +0530 From: Sourav Poddar User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.28) Gecko/20120313 Thunderbird/3.1.20 MIME-Version: 1.0 To: Kevin Hilman CC: Grygorii Strashko , , , , , , Subject: Re: [PATCHv2 2/5] driver: serial: omap: prevent runtime PM for "no_console_suspend" References: <1366638237-6880-1-git-send-email-sourav.poddar@ti.com> <1366638237-6880-3-git-send-email-sourav.poddar@ti.com> <51754DD7.6040904@ti.com> <87fvyi8la5.fsf@linaro.org> In-Reply-To: <87fvyi8la5.fsf@linaro.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2795 Lines: 65 Hi Kevin, On Tuesday 23 April 2013 12:06 AM, Kevin Hilman wrote: > Grygorii Strashko writes: > >> On 04/22/2013 04:43 PM, Sourav Poddar wrote: >>> The driver manages "no_console_suspend" by preventing runtime PM >>> during the suspend path, which forces the console UART to stay awake. >>> >>> Signed-off-by: Sourav Poddar >>> --- >>> drivers/tty/serial/omap-serial.c | 5 ++++- >>> 1 files changed, 4 insertions(+), 1 deletions(-) >>> >>> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c >>> index 08332f3..640b14e 100644 >>> --- a/drivers/tty/serial/omap-serial.c >>> +++ b/drivers/tty/serial/omap-serial.c >>> @@ -1582,7 +1582,7 @@ static int serial_omap_runtime_suspend(struct device *dev) >>> struct uart_omap_port *up = dev_get_drvdata(dev); >>> struct omap_uart_port_info *pdata = dev->platform_data; >>> - if (!up) >>> + if (!up || (!console_suspend_enabled&& uart_console(&up->port))) >>> return -EINVAL; >> Hi Sourav, >> No ) You will block Runtime PM for console UART forever, but instead >> it need to be blocked only during suspend - autosuspend should >> continue working. > Correct. > > Sourav, as I mentioned when I suggested this approach, it should be done > *only* during suspend. > Yes, got the point. >> But this will be not easy, again, - >> because System suspend isn't synchronized with Runtime PM (I mean, >> serial_omap_suspend/resume() may be called from one thread and >> serial_omap_runtime_suspend/resume() from another at same time). >> And now, serial_omap_suspend() callback is the only one place where you >> can detect that system is going to sleep. > So set an 'is_suspending' flag in ->suspend (it may need to be in > ->prepare) and clear it in ->resume (->complete), and check the flag in > the ->runtime_supend() callback. It's not uncommon for drivers to have > such a flag for various reasons. > Ok. Will adapt the next version inline with the above suggestions. >> Personally, i don't believe in such approach (my experiences from K3.4 >> said me that there will be more problems than benefits). >> >> And, I like combination of "no_console_suspend" in bootargs + >> "ti,no_idle_on_suspend" for console UART in DT, because 1) it's debug >> option and 2) until >> smth. will be decided about OMAP OCP Bus it can be used. >> >> It's just my opinion. > No, we need to get rid of ti,no_idle_on_suspend. It's an ugly, > OMAP-specific hack (and I'm free to insult it because I introduced it.) > > Kevin > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/