From: Vincent Whitchurch <vincent.whitchurch@axis.com>
To: <wsa@kernel.org>
Cc: <kernel@axis.com>,
Vincent Whitchurch <vincent.whitchurch@axis.com>,
<linux-i2c@vger.kernel.org>, <devicetree@vger.kernel.org>,
<krzk+dt@kernel.org>, <robh+dt@kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH v2 0/2] i2c: Allow disabling auto detection via devicetree
Date: Tue, 12 Apr 2022 10:50:44 +0200 [thread overview]
Message-ID: <20220412085046.1110127-1-vincent.whitchurch@axis.com> (raw)
v2:
- Change subject prefix of bindings patch
- Reword description of property in bindings patch
When a driver with a ->detect callback (such as lm75) is loaded, the i2c core
performs I2C transactions on the bus to all the addresses listed in that
driver's address_list. This kind of probing wastes time and as
Documentation/i2c/instantiating-devices.rst says, this method is not
recommended and it is instead advised to list all devices in the devicetree.
However, even if all the devices are listed in the devicetree, there is
currently no way to prevent the core from attempting auto detection short of
patching controller drivers to not pass the I2C_CLASS* bits in adap->class.
The latter is not always possible since generic drivers like i2c-gpio set these
bits.
To avoid this unnecessary probing and reduce boot time, this series adds a
property to the devicetree and support in the I2C core to allow this feature to
be disabled.
Cc: linux-i2c@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: krzk+dt@kernel.org
Cc: robh+dt@kernel.org
Cc: linux-kernel@vger.kernel.org
Vincent Whitchurch (2):
dt-bindings: i2c: add property to avoid device detection
i2c: core: support no-detect property
Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++
drivers/i2c/i2c-core-base.c | 8 +++++++-
include/linux/i2c.h | 1 +
3 files changed, 12 insertions(+), 1 deletion(-)
--
2.34.1
next reply other threads:[~2022-04-12 9:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 8:50 Vincent Whitchurch [this message]
2022-04-12 8:50 ` [PATCH v2 1/2] dt-bindings: i2c: add property to avoid device detection Vincent Whitchurch
2022-04-12 8:52 ` Krzysztof Kozlowski
2022-04-12 21:22 ` Rob Herring
2022-04-14 8:55 ` Vincent Whitchurch
2022-04-14 19:40 ` Rob Herring
2022-05-14 14:26 ` Wolfram Sang
2022-05-16 6:43 ` Vincent Whitchurch
2022-05-16 7:12 ` Wolfram Sang
2022-05-16 7:57 ` Peter Rosin
2022-05-16 8:07 ` Peter Rosin
2022-05-18 16:09 ` Luca Ceresoli
2022-04-12 8:50 ` [PATCH v2 2/2] i2c: core: support no-detect property Vincent Whitchurch
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