Re: [PATCH v2] can: c_can: Use platform id data when OF data is absent

["Uwe Kleine-König" <u.kleine-koenig@baylibre.com>]

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Hello,

On Thu, Jun 25, 2026 at 01:41:52PM +0800, Pengpeng Hou wrote:
> The platform driver keeps controller metadata in both the OF match table
> and the platform id table. Probe reads the metadata with
> device_get_match_data(), which does not fall back to platform id-table
> driver_data.
> 
> When the device is matched through the platform id table, drvdata can
> therefore be NULL before it is dereferenced for msg_obj_num and the
> controller type. Fall back to platform_get_device_id() when firmware
> match data is not available.
> 
> Fixes: 5e6c3454b405 ("net: can: Use device_get_match_data()")
> Cc: stable@vger.kernel.org
> Reviewed-by: Vincent Mailhol <mailhol@kernel.org>
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
> Changes in v2:
> - Add the Fixes tag requested by Vincent.
> - Scope the platform id variable inside the fallback block.
> - Carry Vincent's Reviewed-by for the requested v2 shape.
> 
>  drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index 19c86b94a40e..8a0c88839d24 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -267,6 +267,14 @@ static int c_can_plat_probe(struct platform_device *pdev)
>  	struct device_node *np = pdev->dev.of_node;
>  
>  	drvdata = device_get_match_data(&pdev->dev);
> +	if (!drvdata) {
> +		const struct platform_device_id *id;
> +
> +		id = platform_get_device_id(pdev);
> +		if (!id)
> +			return -ENODEV;
> +		drvdata = (const struct c_can_driver_data *)id->driver_data;
> +	}

Given that there are no devices probed via the platform_driver's
id_table (or my grep misses it:

	$ git grep -E '"(c_can_platform|c_can|d_can)"'
	drivers/net/can/c_can/c_can_platform.c:         .name = "c_can",
	drivers/net/can/c_can/c_can_platform.c:         .name = "d_can",
)

just do:

	if (!drvdata)
		return -ENODEV;

and drop c_can_id_table[].

An error message would be nice, but the other error exits don't have one
either.

Unless I missed something a backport to stable isn't needed then,
either.

Best regards
Uwe

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