Re: [PATCHv3 0/3] OMAP UART: Adding support for omap-serial driver.

From: Tony Lindgren <tony@atomide.com>
To: Olof Johansson <olof@lixom.net>
Cc: "G, Manjunath Kondaiah" <manjugk@ti.com>,
	"Shilimkar, Santosh" <santosh.shilimkar@ti.com>,
	Govindraj <govindraj.ti@gmail.com>,
	"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
	"Pandita, Vikram" <vikram.pandita@ti.com>,
	"Raja, Govindraj" <govindraj.raja@ti.com>
Subject: Re: [PATCHv3 0/3] OMAP UART: Adding support for omap-serial driver.
Date: Wed, 25 Nov 2009 09:40:45 -0800	[thread overview]
Message-ID: <20091125174044.GD4348@atomide.com> (raw)
In-Reply-To: <4B0CD762.70707@lixom.net>

* Olof Johansson <olof@lixom.net> [091124 23:05]:
> G, Manjunath Kondaiah wrote:
> >>>You should allow both of them to be enabled at the same time, so the
> >>>same
> >>>kernel can for example be booted on a ZOOM2 with debug board
> >>>attached
> >>>(8250 on GPMC), or on a beagle/overo board.
> >>>
> >>>Making them exclusive would be a step backwards.
> >>More so, selecting both config option really shouldn't break the
> >>build. If one expect a build break because only one of the
> >>options can be enabled then clearly the dependency should be
> >>used so that user can select only one option at a time.
> >
> >Ack. There should be dependency in Kconfig so that user can select
> >either 8250 console(through Quad-uart for zoom2/zoom3) or OMAP-serial
> >Console(through OMAP UART's).
> 
> No. The drivers MUST handle co-existing. You can have a bunch of
> drivers configured to be _potential_ consoles, which one will end up
> being used depends on, among other things, the bootargs. But it
> should be allowed to configure both 8250 and omap-serial at the same
> time.

Exactly. Even the same board must be capable of using 8250 and
omap-serial. That's why it must be called ttyO instead of ttyS.
The 8250 drivers are often needed for hotpluggable buses.

Regards,

Tony