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Message-ID: <CAA8EJppKou84MZm0JS_4bPveMO2UxpMs5ejCoL7OMWd-umtDmQ@mail.gmail.com>
Date: Thu, 31 Oct 2024 20:23:00 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>, freedreno@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org, robdclark@...il.com, swboyd@...omium.org,
airlied@...il.com, quic_jesszhan@...cinc.com, lyude@...hat.com,
simona@...ll.ch, linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] i2c: skip of_i2c_register_device() for invalid child nodes
On Wed, 30 Oct 2024 at 03:07, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>
> of_i2c_register_devices() adds all child nodes of a given i2c bus
> however in certain device trees of_alias_from_compatible() and
> of_property_read_u32() can fail as the child nodes of the device
> might not be valid i2c client devices. One such example is the
> i2c aux device for the DRM MST toplogy manager which uses the
> display controller device node to add the i2c adaptor [1] leading
> to an error spam like below
>
> i2c i2c-20: of_i2c: register /soc@...isplay-subsystem@...0000/display-controller@...1000/ports
> i2c i2c-20: of_i2c: modalias failure on /soc@...isplay-subsystem@...0000/display-controller@...1000/ports
> i2c i2c-20: Failed to create I2C device for /soc@...isplay-subsystem@...0000/display-controller@...1000/ports
> i2c i2c-20: of_i2c: register /soc@...isplay-subsystem@...0000/display-controller@...1000/opp-table
> i2c i2c-20: of_i2c: invalid reg on /soc@...isplay-subsystem@...0000/display-controller@...1000/opp-table
> i2c i2c-20: Failed to create I2C device for /soc@...isplay-subsystem@...0000/display-controller@...1000/opp-table
>
> Add protection against invalid child nodes before trying to register
> i2c devices for all child nodes.
>
> [1] : https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/display/drm_dp_mst_topology.c#L5985
>
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
> drivers/i2c/i2c-core-of.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c
> index a6c407d36800..62a2603c3092 100644
> --- a/drivers/i2c/i2c-core-of.c
> +++ b/drivers/i2c/i2c-core-of.c
> @@ -86,6 +86,8 @@ void of_i2c_register_devices(struct i2c_adapter *adap)
> {
> struct device_node *bus, *node;
> struct i2c_client *client;
> + u32 addr;
> + char temp[16];
>
> /* Only register child devices if the adapter has a node pointer set */
> if (!adap->dev.of_node)
> @@ -101,6 +103,10 @@ void of_i2c_register_devices(struct i2c_adapter *adap)
> if (of_node_test_and_set_flag(node, OF_POPULATED))
> continue;
>
> + if (of_property_read_u32(node, "reg", &addr) ||
> + of_alias_from_compatible(node, temp, sizeof(temp)))
> + continue;
I think just of_property_read_u32() should be enough to skip
non-I2C-device children. If of_alias_from_compatible() fails, it is a
legit error.
> +
> client = of_i2c_register_device(adap, node);
> if (IS_ERR(client)) {
> dev_err(&adap->dev,
> --
> 2.34.1
>
--
With best wishes
Dmitry
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