Re: [PATCH 4/6] ARM: i.MX6: skov: fix LVDS deep probe

[Marco Felsch <m.felsch@pengutronix.de>]

On 22-12-22, Ahmad Fatoum wrote:
> With deep probe, barebox will have registered most drivers by the time
> it walks the device tree and will then keep probing devices on demand.
> 
> This simplifies the common case of devices having dependencies on each
> other, but on the other hand expects board code to be deep probe aware.
> 
> The Skov board code already takes care to explicitly probe the GPIO
> controllers it requires, but it also optionally enables and registers
> devices that were initially disabled in the device tree.
> 
> It's paramount that devices are only registered _after_ the relevant
> device tree parts are rewritten. This was currently not accounted for,
> which led to LDB device being probed before its child lvds-channel node
> was enabled: We thus ended up with a LDB device, what the driver
> couldn't do anything with:
> 
>   mode_name: invalid:0 (type: enum)
> 
> Fixes: 31d2289da2f3 ("ARM: boards: skov-imx6: start using deep-probe")
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>

> ---
>  arch/arm/boards/skov-imx6/board.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/boards/skov-imx6/board.c b/arch/arm/boards/skov-imx6/board.c
> index 7ddc6e937b0b..8f4d7efe4278 100644
> --- a/arch/arm/boards/skov-imx6/board.c
> +++ b/arch/arm/boards/skov-imx6/board.c
> @@ -474,14 +474,15 @@ static void skov_init_ldb(void)
>  		return;
>  	}
>  
> -	of_device_enable_and_register(ldb);
> -
> -	/* ... as well as its channel 0 */
> +	/* First enable channel 0, prior to enabling parent */
>  	chan = of_find_node_by_name_address(ldb, "lvds-channel@0");
>  	if (chan)
>  		of_device_enable(chan);
>  	else
>  		dev_err(skov_priv->dev, "Cannot find \"lvds-channel@0\" node\n");
> +
> +	/* Now probe will see the expected device tree */
> +	of_device_enable_and_register(ldb);
>  }
>  
>  /*
> -- 
> 2.30.2
> 
> 
>