Re: [PATCH v2 1/5] clk: qcom: clk-alpha-pll: Remove unnecessary cast

Bjorn Andersson
2019-06-17T04:36:47Z

On Wed 12 Jun 02:17 PDT 2019, Vinod Koul wrote:

> We have couple of instances in the driver with unnecessary
> u64 casts, drop them.
>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
> drivers/clk/qcom/clk-alpha-pll.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index 0ced4a5a9a17..b48707693ffd 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -832,7 +832,7 @@ static int clk_alpha_pll_postdiv_set_rate(struct clk_hw *hw, unsigned long rate,
> int div;
>
> /* 16 -> 0xf, 8 -> 0x7, 4 -> 0x3, 2 -> 0x1, 1 -> 0x0 */
> - div = DIV_ROUND_UP_ULL((u64)parent_rate, rate) - 1;
> + div = DIV_ROUND_UP_ULL(parent_rate, rate) - 1;

Afaict DIV_ROUND_UP_ULL() will first add "parent_rate" and "rate" and
then stash this in a unsigned long long and do the division. So what
happens if parent_rate + rate > 32 bits on a 32-bit target?

(Shouldn't there be a cast of (ll) in the macro to ULL?)

Regards,
Bjorn

>
> return regmap_update_bits(pll->clkr.regmap, PLL_USER_CTL(pll),
> PLL_POST_DIV_MASK(pll) << PLL_POST_DIV_SHIFT,
> @@ -1094,7 +1094,7 @@ static int clk_alpha_pll_postdiv_fabia_set_rate(struct clk_hw *hw,
> return -EINVAL;
> }
>
> - div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
> + div = DIV_ROUND_UP_ULL(parent_rate, rate);
> for (i = 0; i < pll->num_post_div; i++) {
> if (pll->post_div_table[i].div == div) {
> val = pll->post_div_table[i].val;
> --
> 2.20.1
>