RE: [PATCH] clk: samsung: Fix pll36xx_recalc_rate to handle kdivproperly

From: Kukjin Kim
Date: Wed Jun 05 2013 - 07:51:36 EST


Doug Anderson wrote:
>
> The KDIV value is often listed as unsigned but it needs to be treated
> as a 16-bit signed value when using it in calculations. Fix our rate
> recalculation to do this correctly.
>
> Before doing this, I tried setting EPLL on exynos5250 to:
> rate, m, p, s, k = 80000000, 107, 2, 4, 43691
>
> This rate is exactly from the table in the exynos5250 user manual.
>
> I read this back as 80750003 with:
> cat /sys/kernel/debug/clk/fin_pll/fout_epll/clk_rate
>
> After this patch, it reads back as 80000003
>
> mw 0x10020130 a06b0204
> mw 0x10020134 0000aaab
>
> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>

Yeah,

Acked-by: Kukjin Kim <kgene.kim@xxxxxxxxxxx>

Mike, please apply in your fixes.

Thanks.

- Kukjin

> ---
> This patch is based upon another in-flight patch to avoid conflicts:
> clk: samsung: Use clk->base instead of directly using clk->con0 for
> PLL3xxx
> https://patchwork.kernel.org/patch/2629751/
>
> drivers/clk/samsung/clk-pll.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/samsung/clk-pll.c b/drivers/clk/samsung/clk-pll.c
> index 01f17cf..26416bb 100644
> --- a/drivers/clk/samsung/clk-pll.c
> +++ b/drivers/clk/samsung/clk-pll.c
> @@ -115,7 +115,8 @@ static unsigned long
> samsung_pll36xx_recalc_rate(struct clk_hw *hw,
> unsigned long parent_rate)
> {
> struct samsung_clk_pll *pll = to_clk_pll(hw);
> - u32 mdiv, pdiv, sdiv, kdiv, pll_con0, pll_con1;
> + u32 mdiv, pdiv, sdiv, pll_con0, pll_con1;
> + s16 kdiv;
> u64 fvco = parent_rate;
>
> pll_con0 = pll_readl(pll, PLL36XX_CON0_OFFSET);
> @@ -123,7 +124,7 @@ static unsigned long
> samsung_pll36xx_recalc_rate(struct clk_hw *hw,
> mdiv = (pll_con0 >> PLL36XX_MDIV_SHIFT) & PLL36XX_MDIV_MASK;
> pdiv = (pll_con0 >> PLL36XX_PDIV_SHIFT) & PLL36XX_PDIV_MASK;
> sdiv = (pll_con0 >> PLL36XX_SDIV_SHIFT) & PLL36XX_SDIV_MASK;
> - kdiv = pll_con1 & PLL36XX_KDIV_MASK;
> + kdiv = (s16)(pll_con1 & PLL36XX_KDIV_MASK);
>
> fvco *= (mdiv << 16) + kdiv;
> do_div(fvco, (pdiv << sdiv));
> --
> 1.8.2.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/