Re: [PATCH v2 02/10] clk: qcom: Add support for alpha pll hwfsm ops

Stephen Boyd
2016-08-24T06:14:06Z

On 08/11, Rajendra Nayak wrote:
> Add support to enable/disable the alpha pll using hwfsm

Care to add some more description here about what's going on?

>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> ---
> drivers/clk/qcom/clk-alpha-pll.c | 109 ++++++++++++++++++++++++++++++++++-----
> drivers/clk/qcom/clk-alpha-pll.h | 1 +
> 2 files changed, 98 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index e6a03ea..bae31f9 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -62,9 +62,10 @@
> #define to_clk_alpha_pll_postdiv(_hw) container_of(to_clk_regmap(_hw), \
> struct clk_alpha_pll_postdiv, clkr)
>
> -static int wait_for_pll(struct clk_alpha_pll *pll)
> +static int wait_for_pll(struct clk_alpha_pll *pll, u32 mask, bool inverse,
> + const char *action)
> {
> - u32 val, mask, off;
> + u32 val, off;
> int count;
> int ret;
> const char *name = clk_hw_get_name(&pll->clkr.hw);
> @@ -74,26 +75,101 @@ static int wait_for_pll(struct clk_alpha_pll *pll)
> if (ret)
> return ret;
>
> - if (val & PLL_VOTE_FSM_ENA)
> - mask = PLL_ACTIVE_FLAG;
> - else
> - mask = PLL_LOCK_DET;
> -
> - /* Wait for pll to enable. */

Perhaps commit text could state why we shouldn't keep extending
this model of figuring out what to poll?

> for (count = 100; count > 0; count--) {
> ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &val);
> if (ret)
> return ret;
> - if ((val & mask) == mask)
> + if (inverse && (val & mask))
> + return 0;
> + else if ((val & mask) == mask)
> return 0;
>
> udelay(1);
> }
>
> - WARN(1, "%s didn't enable after voting for it!\n", name);
> + WARN(1, "%s failed to %s!\n", name, action);
> return -ETIMEDOUT;
> }
>
> +static int wait_for_pll_enable(struct clk_alpha_pll *pll, u32 mask)
> +{
> + return wait_for_pll(pll, mask, 0, "enable");
> +}

This is only called with two masks, so maybe we can have two
functions for it or a simple macro to avoid making clients know
about the mask?

> +
> +static int wait_for_pll_disable(struct clk_alpha_pll *pll, u32 mask)
> +{
> + return wait_for_pll(pll, mask, 1, "disable");
> +}
> +
> +static int wait_for_pll_offline(struct clk_alpha_pll *pll, u32 mask)
> +{
> + return wait_for_pll(pll, mask, 0, "offline");
> +}

These two are only called with one mask, why have that as a parameter?

> +
> +/* alpha pll with hwfsm support */
> +#define PLL_OFFLINE_REQ BIT(7)
> +#define PLL_FSM_ENA BIT(20)
> +#define PLL_OFFLINE_ACK BIT(28)
> +#define PLL_ACTIVE_FLAG BIT(30)

Please put these up top next to the register that they're for.

> +
> +static int clk_alpha_pll_hwfsm_enable(struct clk_hw *hw)
> +{
> + int ret;
> + u32 val, off;
> + struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> +
> + off = pll->offset;
> + ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &val);
> + if (ret)
> + return ret;
> +
> + /* Enable HW FSM mode, clear OFFLINE request */

That's pretty obvious.

> + val |= PLL_FSM_ENA;
> + val &= ~PLL_OFFLINE_REQ;
> + ret = regmap_write(pll->clkr.regmap, off + PLL_MODE, val);
> + if (ret)
> + return ret;
> +
> + /* Make sure enable request goes through before waiting for update */
> + mb();
> +
> + ret = wait_for_pll_enable(pll, PLL_ACTIVE_FLAG);
> + if (ret)
> + return ret;
> +
> + return 0;

Simplify to return wait_for_pll_enable()?

--
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