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