From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: khali@linux-fr.org
Cc: Greg KH <greg@kroah.com>,
Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: i2c/ smbus question
Date: Sun, 08 Jan 2006 09:36:03 +1100 [thread overview]
Message-ID: <1136673364.30123.20.camel@localhost.localdomain> (raw)
Hi !
Can you confirm the difference between writing a block of data with
I2C_SMBUS_BLOCK_DATA vs I2C_SMBUS_I2C_BLOCK_DATA on the wire ? It's my
understanding that the former will actually send the lenght byte on the
wire before the data while the later won't, though they both send a
subaddress.
I'm completely rewriting the powermac i2c support (consolidating all
busses behind a low level layer that I need to use in circumstances
where the linux i2c layer isn't useable, and with a single driver in
drivers/i2c/busses/* replacing i2c-keywest.c and i2c-pmac-smu.c) and I
think I'm hitting a problem where i2c-keywest didn't implement
I2C_SMBUS_BLOCK_DATA properly (didn't send the lenght byte) and some
drivers (our sound drivers) rely on that behaviour (that's fine, I can
fix them too, I just want to make sure I understand what the semantic
should be).
I'm a bit surprised that there seem to be no wrapper for writing with
I2C_SMBUS_I2C_BLOCK_DATA, only for reading, in i2c-core.c since it
appears to me that it's the most common one, at least for all devices
I've dealt with so far (mostly sound & clock chips in addition to
sensors)...
Cheers,
Ben.
next reply other threads:[~2006-01-07 22:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-07 22:36 Benjamin Herrenschmidt [this message]
2006-01-08 10:30 ` i2c/ smbus question Jean Delvare
2006-01-08 21:10 ` Benjamin Herrenschmidt
2006-01-08 22:58 ` Benjamin Herrenschmidt
2006-01-09 3:53 ` Greg KH
2006-01-09 4:19 ` Benjamin Herrenschmidt
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=1136673364.30123.20.camel@localhost.localdomain \
--to=benh@kernel.crashing.org \
--cc=greg@kroah.com \
--cc=khali@linux-fr.org \
--cc=linux-kernel@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