[PATCH 2/2] arm64: dts: marvell: mcbin: enable uart headers - Russell King

From: linux@armlinux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] arm64: dts: marvell: mcbin: enable uart headers
Date: Tue, 30 Jan 2018 16:58:44 +0000	[thread overview]
Message-ID: <20180130165844.GF9418@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20180130164712.qplfkmtimpi44xxa@sapphire.tkos.co.il>

On Tue, Jan 30, 2018 at 06:47:12PM +0200, Baruch Siach wrote:
> Hi Russell,
> 
> On Tue, Jan 30, 2018 at 04:05:17PM +0000, Russell King - ARM Linux wrote:
> > On Tue, Jan 30, 2018 at 10:01:26AM +0200, Baruch Siach wrote:
> > > Add description of the J25 and J27 UART headers of the Macchiatobin. They use
> > > uart peripherals that the CP0 (J25) and CP1 (J27) provides.
> > 
> > The headers are just fed with the GPIO-level signals, which means any
> > industry standard usage would require additional RS232 level shifting
> > hardware.  So, they're certainly not "generic" serial ports.
> > 
> > While these are labelled up as UARTs, there's no reason to dedicate
> > them as such, they could equally be used to connect to a smart battery/
> > UPS system as a SMBus port, or even to control system LEDs / read
> > the status of system buttons.
> > 
> > Do you have an application for these headers?  If not, it's probably
> > best to leave them alone (until we have DT overlay support sorted to
> > allow boot-loader configuration of hardware such as these - which is
> > being worked on for TI and other boards.)
> 
> The console UART on the FTDI CON9 microUSB is not accessible when the board is 
> mounted on a COTS ATX enclosure. So some users would like UART access through 
> the UART headers.

Please include this information in the commit log.

I'll also point out that the latest board revision also offers a UART
header for the standard console port too, so even if the microUSB is
not available, the standard console is still usable.

-- 
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