From: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
To: Harini Katakam
<harinikatakamlinux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
"grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org"
<grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
"robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org"
<robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Pawel Moll <Pawel.Moll-5wv7dgnIgG8@public.gmane.org>,
"ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org"
<ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>,
"galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org"
<galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
"michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org"
<michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org>,
"soren.brinkmann-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org"
<soren.brinkmann-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"vishnum-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org"
<vishnum-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C
Date: Tue, 2 Dec 2014 14:16:11 +0100 [thread overview]
Message-ID: <20141202131611.GC4072@katana> (raw)
In-Reply-To: <CAFcVECJwFoFd6GrmF282CG+fELnYb=FNCTDq=RYKky_dHha=Jg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
[-- Attachment #1: Type: text/plain, Size: 888 bytes --]
> But given the bugs, it will be useful to just disable it if the system doesn't
> require repeated start.
What do you do when disable repeated start? Sending STOP and START? If
so, this is really something different than repeated start. By using
I2C_FUNC_I2C a user expects repeated start, so if the HW does not
support it, we should say so and don't try to emulate it with something
different.
> If you think DT entry is not the way to go, do you think a CONFIG option or
> something better will work?
No, check at runtime if the transfer is possible on this HW. Bail out if
not.
> We chose a DT property because there is a good chance the user has multiple
> cadence I2C controllers - one connected to a slave that needs repeated start
> (like a power controller) and another that doesn't care.
The user should not need to know with this level of detail if we can
avoid it IMO.
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: wsa@the-dreams.de (Wolfram Sang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C
Date: Tue, 2 Dec 2014 14:16:11 +0100 [thread overview]
Message-ID: <20141202131611.GC4072@katana> (raw)
In-Reply-To: <CAFcVECJwFoFd6GrmF282CG+fELnYb=FNCTDq=RYKky_dHha=Jg@mail.gmail.com>
> But given the bugs, it will be useful to just disable it if the system doesn't
> require repeated start.
What do you do when disable repeated start? Sending STOP and START? If
so, this is really something different than repeated start. By using
I2C_FUNC_I2C a user expects repeated start, so if the HW does not
support it, we should say so and don't try to emulate it with something
different.
> If you think DT entry is not the way to go, do you think a CONFIG option or
> something better will work?
No, check at runtime if the transfer is possible on this HW. Bail out if
not.
> We chose a DT property because there is a good chance the user has multiple
> cadence I2C controllers - one connected to a slave that needs repeated start
> (like a power controller) and another that doesn't care.
The user should not need to know with this level of detail if we can
avoid it IMO.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: Digital signature
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20141202/f108c6a4/attachment.sig>
WARNING: multiple messages have this Message-ID (diff)
From: Wolfram Sang <wsa@the-dreams.de>
To: Harini Katakam <harinikatakamlinux@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
"grant.likely@linaro.org" <grant.likely@linaro.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
Pawel Moll <Pawel.Moll@arm.com>,
"ijc+devicetree@hellion.org.uk" <ijc+devicetree@hellion.org.uk>,
"galak@codeaurora.org" <galak@codeaurora.org>,
"michal.simek@xilinx.com" <michal.simek@xilinx.com>,
"soren.brinkmann@xilinx.com" <soren.brinkmann@xilinx.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"vishnum@xilinx.com" <vishnum@xilinx.com>
Subject: Re: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C
Date: Tue, 2 Dec 2014 14:16:11 +0100 [thread overview]
Message-ID: <20141202131611.GC4072@katana> (raw)
In-Reply-To: <CAFcVECJwFoFd6GrmF282CG+fELnYb=FNCTDq=RYKky_dHha=Jg@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 888 bytes --]
> But given the bugs, it will be useful to just disable it if the system doesn't
> require repeated start.
What do you do when disable repeated start? Sending STOP and START? If
so, this is really something different than repeated start. By using
I2C_FUNC_I2C a user expects repeated start, so if the HW does not
support it, we should say so and don't try to emulate it with something
different.
> If you think DT entry is not the way to go, do you think a CONFIG option or
> something better will work?
No, check at runtime if the transfer is possible on this HW. Bail out if
not.
> We chose a DT property because there is a good chance the user has multiple
> cadence I2C controllers - one connected to a slave that needs repeated start
> (like a power controller) and another that doesn't care.
The user should not need to know with this level of detail if we can
avoid it IMO.
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
next prev parent reply other threads:[~2014-12-02 13:16 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-02 10:05 [PATCH 0/4] Cadence I2C driver fixes Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-02 10:05 ` [PATCH 1/4] i2c: cadence: Handle > 252 byte transfers Harini Katakam
2014-12-02 10:05 ` Harini Katakam
[not found] ` <1417514749-24319-1-git-send-email-harinik-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org>
2014-12-02 10:05 ` [PATCH 2/4] i2c: cadence: Set the hardware time-out register to maximum value Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-03 11:28 ` Wolfram Sang
2014-12-03 11:28 ` Wolfram Sang
2014-12-02 10:05 ` [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-02 11:19 ` Mark Rutland
2014-12-02 11:19 ` Mark Rutland
2014-12-02 12:13 ` Harini Katakam
2014-12-02 12:13 ` Harini Katakam
2014-12-02 12:13 ` Harini Katakam
[not found] ` <CAFcVECLtPx6shBXJbg9Uf_8fnhkMoO1zpoxGcdda7PSA7z_2rA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-12-02 12:52 ` Wolfram Sang
2014-12-02 12:52 ` Wolfram Sang
2014-12-02 12:52 ` Wolfram Sang
2014-12-02 13:10 ` Harini Katakam
2014-12-02 13:10 ` Harini Katakam
2014-12-02 13:10 ` Harini Katakam
[not found] ` <CAFcVECJwFoFd6GrmF282CG+fELnYb=FNCTDq=RYKky_dHha=Jg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-12-02 13:16 ` Wolfram Sang [this message]
2014-12-02 13:16 ` Wolfram Sang
2014-12-02 13:16 ` Wolfram Sang
2014-12-02 13:30 ` Harini Katakam
2014-12-02 13:30 ` Harini Katakam
2014-12-02 14:15 ` Wolfram Sang
2014-12-02 14:15 ` Wolfram Sang
2014-12-02 15:12 ` Lars-Peter Clausen
2014-12-02 15:12 ` Lars-Peter Clausen
2014-12-02 15:12 ` Lars-Peter Clausen
2014-12-02 10:05 ` [PATCH 4/4] i2c: cadence: Defeature repeated start based on devicetree property Harini Katakam
2014-12-02 10:05 ` Harini Katakam
2014-12-02 10:05 ` Harini Katakam
[not found] ` <1417514749-24319-5-git-send-email-harinik-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org>
2014-12-02 11:21 ` Mark Rutland
2014-12-02 11:21 ` Mark Rutland
2014-12-02 11:21 ` Mark Rutland
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=20141202131611.GC4072@katana \
--to=wsa-z923lk4zbo2bacvfa/9k2g@public.gmane.org \
--cc=Pawel.Moll-5wv7dgnIgG8@public.gmane.org \
--cc=devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org \
--cc=grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org \
--cc=harinikatakamlinux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org \
--cc=ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org \
--cc=linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org \
--cc=linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=mark.rutland-5wv7dgnIgG8@public.gmane.org \
--cc=michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org \
--cc=robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
--cc=soren.brinkmann-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org \
--cc=vishnum-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.