Re: [PATCH v4 2/3] of: base: register DT root as device

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Oleksij,

On 7/20/20 8:39 AM, Oleksij Rempel wrote:
> A usual board file contains at least one of_machine_is_compatible().
> Some of the have a rather long list with complicated version logic.
> 
> To avoid own implementation for driver management, register the root node
> of device tree as platform device. So, the main platform bus can attach
> proper board driver. After this patch a typical board.c file can reuse
> existing driver infrastructure.
> 
> After this patch, you will be able to see all registered board drivers
> with drvinfo as fallow:

this patch breaks boot on the Linux Automation MC-1.
of_platform_device_create() uses of_device_make_bus_id() to generate
a name, but that function is a no-op for the root node.

This results in a platform device with dev->name == NULL, which
inside register_device() -> get_device_by_name_id() -> strcmp
leads to a NULL pointer dereference.

You should probably not use of_platform_device_create, but use
platform_device_register directly and set a suitable name
upfront in the struct device_d you initialize.

Cheers
Ahmad

> ...
> board-embest-riot
> board-protonic-imx6
>     machine.of
> ...
> 
> With devinfo, you'll be able to get some board specific information,
> if this is implemented:
> barebox@Protonic PRTI6Q board:/ devinfo machine.of
> Driver: board-protonic-imx6
> Bus: platform
> Parameters:
>   boardid: 0 (type: uint32)
>   boardrev: 1 (type: uint32)
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  drivers/of/base.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 4754fcb98f..b76e424da0 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2141,6 +2141,7 @@ static void of_probe_memory(void)
>  int of_probe(void)
>  {
>  	struct device_node *firmware;
> +	struct device_d *dev;
>  
>  	if(!root_node)
>  		return -ENODEV;
> @@ -2157,6 +2158,10 @@ int of_probe(void)
>  	if (firmware)
>  		of_platform_populate(firmware, NULL, NULL);
>  
> +	dev = of_platform_device_create(root_node, NULL);
> +	if (dev)
> +		dev_set_name(dev, "%s.of", "machine");
> +
>  	of_clk_init(root_node, NULL);
>  	of_platform_populate(root_node, of_default_bus_match_table, NULL);
>  
> 

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