From: Leif Lindholm <leif.lindholm@linaro.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Lunn <andrew@lunn.ch>,
"grant.likely@linaro.org" <grant.likely@linaro.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
Ian Campbell <ijc@debian.org>,
"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>
Subject: Re: [PATCH v2 2/2] of: support passing console options with stdout-path
Date: Thu, 27 Nov 2014 13:16:36 +0000 [thread overview]
Message-ID: <20141127131635.GJ2361@bivouac.eciton.net> (raw)
In-Reply-To: <20141127121543.GG857@leverpostej>
On Thu, Nov 27, 2014 at 12:15:43PM +0000, Mark Rutland wrote:
> On Wed, Nov 26, 2014 at 09:48:47PM +0000, Andrew Lunn wrote:
> > On Wed, Nov 26, 2014 at 09:07:33PM +0000, Grant Likely wrote:
> > > On Wed, Nov 26, 2014 at 6:30 PM, Andrew Lunn <andrew@lunn.ch> wrote:
> > > > On Wed, Nov 26, 2014 at 05:40:40PM +0000, Leif Lindholm wrote:
> > > >> Support specifying console options (like with console=ttyXN,<options>)
> > > >> by appending them to the stdout-path property after a separating ':'.
> > > >>
> > > >> Example:
> > > >> stdout-path = "uart0:115200";
> > > >
> > > > Hi Leif
> > > >
> > > > This should be documented somewhere under
> > > > Documentation/devicetree/bindings/
> > > >
> > > > Not sure where thought. Maybe a top level chosen.txt?
> > >
> > > Actually, this one doesn't. It is already documented in ePAPR
> >
> > Hi Grant
> >
> > Humm, do i have an old version of ePAPR?
> >
> > All i see is that in Table 3-4 It says:
> >
> > stdout-path O <string> A string that specifies the full path to the
> > node representing the device to be used for
> > boot console output. If the character ":" is
> > present in the value it terminates the
> > path. The value may be an alias.
> >
> > If the stdin-path property is not specified,
> > stdout-path should be assumed to define the input device.
> >
> > So what is before the : is defined. What comes afterwards,
> > baudrate/parity/bits/flow control does not appear to the defined in
> > ePAPR. Should we not document the extension being added here?
>
> I believe that we should, and it should be relatively trivial to add a
> document stating that the format and meaning of the parts after the ':'
> are device-specific.
Device-specific is a bit broad though?
> So how about Documentation/devicetree/bindings/serial/stdout-path.txt,
> with something like the following:
There is, however, nothing serial-specific about this functionality -
it console-specific.
Could it be bindings/console/stdout-path.txt?
> ---->8----
> Device trees may specify the device to be used for boot console output
> with a stdout-path property under /chosen, as described in ePAPR, e.g.
>
> / {
> chosen {
> stdout-path = "/serial@f00:115200";
> };
>
> serial@f00 {
> compatible = "vendor,some-uart";
> reg = <0xf00 0x10>;
> };
> };
>
> If the character ":" is present in the value, this terminates the path.
> The meaning of any cahracters following the ":" is device-specific, and
> must be specified in the relevant binding documentation.
> ---->8----
>
> The more difficult part is documenting those (and I'm still uneasy about
> conflating the Linux driver command line options with the DT binding for
> that reason).
For the current situation, which _is_ serial-specific, could we then
add a serial/stdout-path.txt describing the mapping to
uart_parse_options - making that interface an implicit requirement for
the use of stdout-path?
/
Leif
next prev parent reply other threads:[~2014-11-27 13:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-26 17:40 [PATCH v2 0/2] of: support passing console options with stdout-path Leif Lindholm
2014-11-26 17:40 ` [PATCH v2 1/2] of: add optional options parameter to of_find_node_by_path() Leif Lindholm
2014-11-26 21:06 ` Grant Likely
2014-11-26 22:19 ` Leif Lindholm
2014-11-26 17:40 ` [PATCH v2 2/2] of: support passing console options with stdout-path Leif Lindholm
2014-11-26 18:30 ` Andrew Lunn
2014-11-26 21:07 ` Grant Likely
2014-11-26 21:48 ` Andrew Lunn
2014-11-27 12:15 ` Mark Rutland
2014-11-27 13:16 ` Leif Lindholm [this message]
2014-11-27 13:41 ` Mark Rutland
2014-11-27 13:45 ` Grant Likely
2014-11-27 13:39 ` Grant Likely
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141127131635.GJ2361@bivouac.eciton.net \
--to=leif.lindholm@linaro.org \
--cc=andrew@lunn.ch \
--cc=devicetree@vger.kernel.org \
--cc=grant.likely@linaro.org \
--cc=ijc@debian.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=plagnioj@jcrosoft.com \
--cc=robh+dt@kernel.org \
--cc=s.hauer@pengutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).