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 <s...@chromium.org>
Reviewed-by: Cédric Le Goater <c...@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,
> };
>
