Re: [PATCH V2 2/4] clk: bcm2835: enable fractional and mash support

[Michael Turquette <mturquette@baylibre.com>]

Hi Martin,

Quoting kernel@martin.sperl.org (2016-01-11 11:55:54)
> @@ -1274,9 +1283,50 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw,
>         struct bcm2835_cprman *cprman = clock->cprman;
>         const struct bcm2835_clock_data *data = clock->data;
>         u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);
> +       u32 ctl, mash;
> +       bool enabled;
> 
> +       spin_lock(&cprman->regs_lock);
> +       /* check if divider is identical, then return */
> +       if (div == cprman_read(cprman, data->div_reg))
> +               goto unlock;
> +
> +       /* it is recommended to only set clock registers when disabled */
> +       ctl = cprman_read(cprman, data->ctl_reg);
> +       enabled = ctl & CM_ENABLE;
> +       if (enabled) {
> +               /* disable clock */
> +               cprman_write(cprman, data->ctl_reg, ctl);

This seems unsafe to me. Any IP block consuming this signal will have
its clock cut without warning!

If you need to enforce this behavior we provide the CLK_SET_RATE_GATE
flag to handle it at the framework level.

Regards,
Mike