Re: [PATCH RFC 1/7] clk: samsung: Add enable/disable operation for PLL36XX clocks

Stephen Boyd
2017-04-22T02:51:27Z

On 04/21, Sylwester Nawrocki wrote:
> The existing enable/disable ops for PLL35XX are made more generic
> and used also for PLL36XX. This fixes issues in the kernel with
> PLL36XX PLLs when the PLL has not been already enabled by bootloader.
>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> ---
> drivers/clk/samsung/clk-pll.c | 85 +++++++++++++++++++++++++------------------
> 1 file changed, 49 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/clk/samsung/clk-pll.c b/drivers/clk/samsung/clk-pll.c
> index 5229089..10c76eb 100644
> --- a/drivers/clk/samsung/clk-pll.c
> +++ b/drivers/clk/samsung/clk-pll.c
> @@ -23,6 +23,10 @@ struct samsung_clk_pll {
> struct clk_hw hw;
> void __iomem *lock_reg;
> void __iomem *con_reg;
> + /* PLL enable control bit offset in @con_reg register */
> + unsigned short enable_offs;
> + /* PLL lock status bit offset in @con_reg register */
> + unsigned short lock_offs;
> enum samsung_pll_type type;
> unsigned int rate_count;
> const struct samsung_pll_rate_table *rate_table;
> @@ -61,6 +65,34 @@ static long samsung_pll_round_rate(struct clk_hw *hw,
> return rate_table[i - 1].rate;
> }
>
> +static int samsung_pll3xxx_enable(struct clk_hw *hw)
> +{
> + struct samsung_clk_pll *pll = to_clk_pll(hw);
> + u32 tmp;
> +
> + tmp = readl_relaxed(pll->con_reg);
> + tmp |= BIT(pll->enable_offs);
> + writel_relaxed(tmp, pll->con_reg);
> +
> + /* wait lock time */
> + do {
> + cpu_relax();
> + tmp = readl_relaxed(pll->con_reg);
> + } while (!(tmp & BIT(pll->lock_offs)));

Not a problem with this patch because we're moving code around,
but this is a potential infinite loop that should have some sort
of timeout so we don't sit here forever trying to see a bit
toggle.

--
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