[PATCH v7 10/11] ARM: hi3xxx: add clk-hi3716

[mturquette@linaro.org (Mike Turquette)]

Quoting zhangfei gao (2013-08-21 18:19:33)
> On Thu, Aug 22, 2013 at 5:43 AM, Mike Turquette <mturquette@linaro.org> wrote:
> > Quoting Haojian Zhuang (2013-08-19 19:31:12)
> >> From: Zhangfei Gao <zhangfei.gao@linaro.org>
> >>
> >> Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> >> Signed-off-by: Zhang Mingjun <zhang.mingjun@linaro.org>
> >> ---
> 
> >> +static int hi3716_clkgate_prepare(struct clk_hw *hw)
> >> +{
> >> +       struct hi3716_clk *clk = to_clk_hi3716(hw);
> >> +       unsigned long flags = 0;
> >> +       u32 reg;
> >> +
> >> +       spin_lock_irqsave(&_lock, flags);
> >> +
> >> +       reg = readl_relaxed(clk->reg);
> >> +       reg &= ~BIT(clk->reset_bit);
> >> +       writel_relaxed(reg, clk->reg);
> >> +
> >> +       spin_unlock_irqrestore(&_lock, flags);
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static void hi3716_clkgate_unprepare(struct clk_hw *hw)
> >> +{
> >> +       struct hi3716_clk *clk = to_clk_hi3716(hw);
> >> +       unsigned long flags = 0;
> >> +       u32 reg;
> >> +
> >> +       spin_lock_irqsave(&_lock, flags);
> >> +
> >> +       reg = readl_relaxed(clk->reg);
> >> +       reg |= BIT(clk->reset_bit);
> >> +       writel_relaxed(reg, clk->reg);
> >> +
> >> +       spin_unlock_irqrestore(&_lock, flags);
> >> +}
> >> +
> >> +static struct clk_ops hi3716_clkgate_ops = {
> >> +       .prepare        = hi3716_clkgate_prepare,
> >> +       .unprepare      = hi3716_clkgate_unprepare,
> >> +};
> >
> > Why .prepare & .unprepare instead of .enable & .disable?
> >
> > Regards,
> > Mike
> 
> Thanks  Mike for the review
> 
> the .enable & .disable is directly use clk_gate_ops.
> 
> +       hi3716_clkgate_ops.enable = clk_gate_ops.enable;
> +       hi3716_clkgate_ops.disable = clk_gate_ops.disable;
> +       hi3716_clkgate_ops.is_enabled = clk_gate_ops.is_enabled;
> +       p_clk->gate.bit_idx = array[1];
> 
> prepare & unprepare is handle reset bit, while enable & disable is
> handle enable bit.
> We have to extend since clk_gate_ops does not consider prepare &
> unprepare, otherwise it would be simpler.

I understand why you made this choice from the perspective of re-using
the existing gate-clock implementation. What I meant in my question is
whether or not handling the reset bit in the .prepare/.unprepare is the
right thing.

For instance if you called clk_enable or clk_disable from within an
interrupt handler would you want to toggle the reset bit in that
instance?

Regards,
Mike

> 
> Thanks