From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Hans Verkuil <hverkuil+cisco@kernel.org>,
linux-i2c@vger.kernel.org,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Jan Dabros <jsd@semihalf.com>, Andi Shyti <andi.shyti@kernel.org>
Subject: Re: i2c-designware: not possible to write to different i2c addresses in one transfer?
Date: Wed, 15 Oct 2025 16:40:53 +0300 [thread overview]
Message-ID: <aO-kZUwqcoqnFfTh@smile.fi.intel.com> (raw)
In-Reply-To: <aO-KuJ_T9cXsNpIh@ninjato>
On Wed, Oct 15, 2025 at 01:51:20PM +0200, Wolfram Sang wrote:
> Hi Hans,
>
> lucky you, I happen to have a board with that controller on the table
> currently :)
>
> > This worked fine for the Raspberry Pi 4B using the broadcom i2c driver, but for
> > the Raspberry Pi 5 using the designware driver it fails with -EINVAL and these
> > kernel messages:
> >
> > [ 272.284689] i2c_designware 1f00074000.i2c: i2c_dw_xfer_msg: invalid target address
>
> Confirmed.
>
> > Looking in i2c-designware-master.c it seems it cannot handle consecutive messages for
> > different addresses.
>
> I agree. I leave the final judgement to the experts (Andy, Mika), but I
> already anticipate that I need to extend the existing
> I2C_AQ_COMB_SAME_ADDR quirk into a more generic one. And set the quirk
> in this driver.
May I ask a dumb question? Why do we need such an awkward transaction
to begin with?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2025-10-18 17:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-15 11:25 i2c-designware: not possible to write to different i2c addresses in one transfer? Hans Verkuil
2025-10-15 11:51 ` Wolfram Sang
2025-10-15 13:40 ` Andy Shevchenko [this message]
2025-10-18 18:17 ` Hans Verkuil
2025-10-18 19:21 ` Andy Shevchenko
2025-10-20 9:41 ` Hans Verkuil
2025-10-19 17:53 ` Wolfram Sang
2025-10-20 7:15 ` Hans Verkuil
2025-10-20 11:59 ` Mika Westerberg
2025-10-20 12:29 ` Hans Verkuil
2025-10-20 12:45 ` Mika Westerberg
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