Re: [PATCH 4/6] clk: Fix rate caching in clk_get_parent_rate()

[Sean Anderson <seanga2@gmail.com>]

On 2/20/23 00:59, Samuel Holland wrote:
> clk_get_rate() can return an error value. Recompute the rate if the
> cached value is an error value.
> 
> Fixes: 4aa78300a025 ("dm: clk: Define clk_get_parent_rate() for clk operations")
> Signed-off-by: Samuel Holland <samuel@sholland.org>
> ---
> 
>   drivers/clk/clk-uclass.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
> index 5bce976b060..9d052e5a814 100644
> --- a/drivers/clk/clk-uclass.c
> +++ b/drivers/clk/clk-uclass.c
> @@ -520,7 +520,8 @@ ulong clk_get_parent_rate(struct clk *clk)
>   		return -ENOSYS;
>   
>   	/* Read the 'rate' if not already set or if proper flag set*/
> -	if (!pclk->rate || pclk->flags & CLK_GET_RATE_NOCACHE)
> +	if (!pclk->rate || IS_ERR_VALUE(pclk->rate) ||
> +	    pclk->flags & CLK_GET_RATE_NOCACHE)
>   		pclk->rate = clk_get_rate(pclk);
>   
>   	return pclk->rate;

The correct fix here is

	/* Read the 'rate' if not already set or if proper flag set*/
	if (!pclk->rate || pclk->flags & CLK_GET_RATE_NOCACHE) {
		rate = clk_get_rate(pclk);
		if (!IS_ERR_VALUE(rate))
			pclk->rate = rate;
	}

	return rate;

No point caching errors.

--Sean