From mboxrd@z Thu Jan  1 00:00:00 1970
From: Weijie Gao <weijie.gao@mediatek.com>
Date: Tue, 6 Nov 2018 10:48:01 +0800
Subject: [U-Boot] [PATCH v3 14/18] serial: 16550: allow the driver to
 support MediaTek serial
In-Reply-To: <1541407077.8633.0.camel@mtkswgap22>
References: <cover.1541171496.git.ryder.lee@mediatek.com>
 <9031af7d284f63d8d3e7c5f1d6883ba160b72c46.1541171496.git.ryder.lee@mediatek.com>
 <CAPnjgZ1i+TiGT9WxwnS-ENsMj-Sjr4kJG_WnkkkUyZxqUXNRdA@mail.gmail.com>
 <1541384421.27315.6.camel@mtkswgap22> <1541407077.8633.0.camel@mtkswgap22>
Message-ID: <1541472481.25021.11.camel@mcddlt001>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

On Mon, 2018-11-05 at 16:37 +0800, Ryder Lee wrote:
> On Mon, 2018-11-05 at 10:20 +0800, Ryder Lee wrote:
> > On Sat, 2018-11-03 at 00:09 -0600, Simon Glass wrote:
> > > Hi Ryder,
> > > 
> > > On 2 November 2018 at 09:15, Ryder Lee <ryder.lee@mediatek.com> wrote:
> > > > This patch adds an extra operation in ns16550.c to suuport MediaTek
> > > > SoCs as we have a highspeed register which influences the calcualtion
> > > > of the divisor.
> > > >
> > > > Note that we don't support the baudrate greater than 115200 currently.
> > > >
> > > > Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> > > > Tested-by: Matthias Brugger <matthias.bgg@gmail.com>
> > > > Reviewed-by: Simon Glass <sjg@chromium.org>
> > > > ---
> > > >  drivers/serial/ns16550.c | 10 ++++++++++
> > > >  1 file changed, 10 insertions(+)
> > > 
> > > Actually it seems to me that we should have a compatible string for
> > > this and deal with this at run-time?
> > > 
> > > Is that easy to do here?
> > > 
> > 
> > How about this:
> > 
> > uart0: serial at 11002000 { 
> > 	compatible = "ns16550a"; 
> > 	....
> > 	mediatek,highspeed = <0>; 
> > 	....
> > 
> > Ryder
> > 
> 
> Sorry, I didn't get it right. I will add a compatible string in
> ns16550_serial_ids[] for MTK chips.
> 
> Ryder
> 
> 

Hi Simon,

We have tried the compatible string, but it made the ns16550 driver more
complicated.

To use the compatible string we have to add a new field in
ns16550_platdata, and change the flow of ns16550_serial_probe.
Moreover, it's totally useless for debug uart.

At present using a macro is the easiest way here.

Weijie