linux-kernel - Re: [PATCHv3] driver: serial: prevent UART console idle on suspend while using "no_console

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Date:	Fri, 05 Apr 2013 10:40:29 -0700
From:	Kevin Hilman <khilman@...aro.org>
To:	Sourav Poddar <sourav.poddar@...com>
Cc:	<gregkh@...uxfoundation.org>, <tony@...mide.com>,
	<rmk+kernel@....linux.org.uk>, <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-serial@...r.kernel.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Felipe Balbi <balbi@...com>, Rajendra nayak <rnayak@...com>
Subject: Re: [PATCHv3] driver: serial: prevent UART console idle on suspend while using "no_console_suspend"

Sourav Poddar <sourav.poddar@...com> writes:

> With dt boot, uart wakeup after suspend is non functional while using
> "no_console_suspend" in the bootargs. With "no_console_suspend" used, we
> should prevent the runtime suspend of the uart port which is getting used
> as an console.
>
> Cc: Santosh Shilimkar<santosh.shilimkar@...com>
> Cc: Felipe Balbi<balbi@...com>
> Cc: Rajendra nayak<rnayak@...com>
> Tested on omap5430evm, omap4430sdp.
>
> Signed-off-by: Sourav Poddar <sourav.poddar@...com>

Rather than make these special checks inside the driver's runtime PM
callbacks, you should just disable runtime PM (pm_runtime_disable())

Then, this should be broken into 2 patches.

1) serial core: add the '->is_console' flag.  (nit on naming: don't call
   it port_is_console, since the struct is already a uart_port)

2) In the OMAP UART driver's ->prepare callback, check the is_console flag
   and pm_runtime_disable() accordingly  (then pm_runtime_enable() in
   the drivers's ->complete callback.

Kevin
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