From: Vitor Soares <Vitor.Soares@synopsys.com>
To: Boris Brezillon <boris.brezillon@collabora.com>,
Vitor Soares <Vitor.Soares@synopsys.com>
Cc: "linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>,
"joao.pinto@synopsys.com" <Joao.Pinto@synopsys.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
Boris Brezillon <bbrezillon@kernel.org>
Subject: RE: [PATCH 1/3] i3c: fix i2c and i3c scl rate by bus mode
Date: Mon, 22 Apr 2019 17:54:29 +0000 [thread overview]
Message-ID: <13D59CF9CEBAF94592A12E8AE55501350A61C415@DE02WEMBXB.internal.synopsys.com> (raw)
In-Reply-To: <20190422180715.40abe1b9@collabora.com>
From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Mon, Apr 22, 2019 at 17:07:15
> On Mon, 22 Apr 2019 15:54:33 +0000
> Vitor Soares <Vitor.Soares@synopsys.com> wrote:
>
>
> > > > >
> > > > > > {
> > > > > > i3cbus->mode = mode;
> > > > > >
> > > > > > - if (!i3cbus->scl_rate.i3c)
> > > > > > - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > > > -
> > > > > > - if (!i3cbus->scl_rate.i2c) {
> > > > > > - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
> > > > > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> > > > > > - else
> > > > > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> > > > > > + switch (i3cbus->mode) {
> > > > > > + case I3C_BUS_MODE_PURE:
> > > > > > + if (!i3cbus->scl_rate.i3c)
> > > > > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > > > + break;
> > > > > > + case I3C_BUS_MODE_MIXED_FAST:
> > > > > > + if (!i3cbus->scl_rate.i3c)
> > > > > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > > > + if (!i3cbus->scl_rate.i2c)
> > > > > > + i3cbus->scl_rate.i2c = i2c_scl_rate;
> > > > > > + break;
> > > > > > + case I3C_BUS_MODE_MIXED_SLOW:
> > > > > > + if (!i3cbus->scl_rate.i2c)
> > > > > > + i3cbus->scl_rate.i2c = i2c_scl_rate;
> > > > > > + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> > > > >
> > > > > Maybe we should do
> > > > >
> > > > > if (!i3cbus->scl_rate.i3c ||
> > > > > i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
> > > > > i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> > > > >
> > > > > Just in case the I3C rate forced by the user is lower than the max I2C
> > > > > rate.
> > > >
> > > > That was something that I considered but TBH it isn't a real use case.
> > >
> > > Add a WARN_ON() to at least catch such inconsistencies. And maybe we
> > > should add a dev_warn() when the user-defined rates do not match
> > > the mode/LVR constraints. It's easy to do a mistake when writing a dts.
> >
> > I think the WARN_ON() is too evasive on the screen and won't provide the
> > information we want.
> > The dev_warn() should work perfectly here.
> >
> > if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
> > dev_warn(&i3cbus->cur_master->dev->dev,
> > "%s: i3c-scl-hz lower then i2c-scl-hz\n", __func__);
>
> Using dev_warn() sounds good, though I don't think you need the
> __func__ here. Also, please print the i2c/i3c rates in the message, and
> align the second line on the open parens.
>
> > if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE ||
> > i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE)
> > dev_warn(&i3cbus->cur_master->dev->dev,
> > "%s: i2c-scl-hz not defined according MIPI I3C spec\n",
> > __func__);
>
> Is that really a problem? Having an i2c rate that is less than FM speed
> sounds like a valid case to me.
I'm addressing the spec constrains.
In the practice it can be SM or even HS, it depends on the interface.
>
> >
> > Maybe it make more sense to do this check on of_populate_i3c_bus(), what
> > do you think?
> >
>
> No, we really want to have this check here, because we might support
> other HW description formats at some point (board-files, ACPI, ...).
Yes, you are right. I forgot that point.
_______________________________________________
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c
next prev parent reply other threads:[~2019-04-22 17:54 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-15 18:46 [PATCH 0/3] Fix i2c and i3c scl rate according bus mode Vitor Soares
2019-04-15 18:46 ` [PATCH 1/3] i3c: fix i2c and i3c scl rate by " Vitor Soares
2019-04-16 5:50 ` Boris Brezillon
2019-04-16 14:24 ` Vitor Soares
2019-04-16 14:52 ` Boris Brezillon
2019-04-22 15:54 ` Vitor Soares
2019-04-22 16:07 ` Boris Brezillon
2019-04-22 17:54 ` Vitor Soares [this message]
2019-04-22 18:27 ` Boris Brezillon
2019-04-22 19:59 ` Vitor Soares
2019-04-15 18:46 ` [PATCH 2/3] i3c: add mixed limited " Vitor Soares
2019-04-16 6:00 ` Boris Brezillon
2019-04-16 14:27 ` Vitor Soares
2019-04-15 18:46 ` [PATCH 3/3] i3c: dw: Add limited bus mode support Vitor Soares
2019-04-16 6:09 ` Boris Brezillon
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=13D59CF9CEBAF94592A12E8AE55501350A61C415@DE02WEMBXB.internal.synopsys.com \
--to=vitor.soares@synopsys.com \
--cc=Joao.Pinto@synopsys.com \
--cc=bbrezillon@kernel.org \
--cc=boris.brezillon@collabora.com \
--cc=linux-i3c@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
/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).