[PATCH 06/19] aspeed: ast2500: Read clock ofdata in the correct method

[Cédric Le Goater]

On 12/30/19 5:19 AM, Simon Glass wrote:
> At present the clock driver reads its ofdata in the probe() method. This
> is not correct although it is often harmless.
> 
> However in this case it causes a problem, something like this:
> 
> - ast_get_scu() is called (from somewhere) to get the SCI address
> - this probes the clock
>    - first sets up ofdata (which does nothing at present)
>    - DM marks clock device as active
>    - DM calls pinctrl
>       - pinctrl probes and calls ast_get_scu() in ast2500_pinctrl_probe()
>       - ast_get_scu() probes the clock, but sees it already marked as
>            probed
>       - ast_get_scu() accesses the clock's private data, with scu as NULL
>    - DM calls clock probe function ast2500_clk_probe() which reads scu
> 
> By putting the read of scu into the correct method, scu is read as part of
> ofdata setup, and everything is OK.
> 
> Note: This problem did not matter until now since DM always probed all
> parents before reading a child's ofdata. The fact that pinctrl is a child
> of clock seems to trigger this strange bug.

Did you find it with QEMU ?

> 
> Signed-off-by: Simon Glass <sjg at chromium.org>

Reviewed-by: Cédric Le Goater <clg at kaod.org>

C.

> ---
> 
>  drivers/clk/aspeed/clk_ast2500.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/aspeed/clk_ast2500.c b/drivers/clk/aspeed/clk_ast2500.c
> index 9249cf9cdf..b3a3f3d4dd 100644
> --- a/drivers/clk/aspeed/clk_ast2500.c
> +++ b/drivers/clk/aspeed/clk_ast2500.c
> @@ -490,7 +490,7 @@ struct clk_ops ast2500_clk_ops = {
>  	.enable = ast2500_clk_enable,
>  };
>  
> -static int ast2500_clk_probe(struct udevice *dev)
> +static int ast2500_clk_ofdata_to_platdata(struct udevice *dev)
>  {
>  	struct ast2500_clk_priv *priv = dev_get_priv(dev);
>  
> @@ -525,5 +525,5 @@ U_BOOT_DRIVER(aspeed_ast2500_scu) = {
>  	.priv_auto_alloc_size = sizeof(struct ast2500_clk_priv),
>  	.ops		= &ast2500_clk_ops,
>  	.bind		= ast2500_clk_bind,
> -	.probe		= ast2500_clk_probe,
> +	.ofdata_to_platdata		= ast2500_clk_ofdata_to_platdata,
>  };
>