On Wed, 2020-05-27 at 17:45 +0200, Maxime Ripard wrote:
> The raspberrypi firmware clock driver has a min_rate / max_rate clamping by
> storing the info it needs in a private structure.
> 
> However, the CCF already provides such a facility, so we can switch to it
> to remove the boilerplate.
> 
> Signed-off-by: Maxime Ripard <max...@cerno.tech>
> ---
>  drivers/clk/bcm/clk-raspberrypi.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-
> raspberrypi.c
> index a20492fade6a..e135ad28d38d 100644
> --- a/drivers/clk/bcm/clk-raspberrypi.c
> +++ b/drivers/clk/bcm/clk-raspberrypi.c
> @@ -36,9 +36,6 @@ struct raspberrypi_clk {
>       struct rpi_firmware *firmware;
>       struct platform_device *cpufreq;
>  
> -     unsigned long min_rate;
> -     unsigned long max_rate;
> -
>       struct clk_hw pllb;
>  };
>  
> @@ -142,13 +139,11 @@ static int raspberrypi_fw_pll_set_rate(struct clk_hw
> *hw, unsigned long rate,
>  static int raspberrypi_pll_determine_rate(struct clk_hw *hw,
>                                         struct clk_rate_request *req)
>  {
> -     struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
> -                                                pllb);
>       u64 div, final_rate;
>       u32 ndiv, fdiv;
>  
>       /* We can't use req->rate directly as it would overflow */
> -     final_rate = clamp(req->rate, rpi->min_rate, rpi->max_rate);
> +     final_rate = clamp(req->rate, req->min_rate, req->max_rate);
>  
>       div = (u64)final_rate << A2W_PLL_FRAC_BITS;
>       do_div(div, req->best_parent_rate);
> @@ -215,12 +210,15 @@ static int raspberrypi_register_pllb(struct
> raspberrypi_clk *rpi)
>       dev_info(rpi->dev, "CPU frequency range: min %u, max %u\n",
>                min_rate, max_rate);
>  
> -     rpi->min_rate = min_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
> -     rpi->max_rate = max_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
> -
>       rpi->pllb.init = &init;
>  
> -     return devm_clk_hw_register(rpi->dev, &rpi->pllb);
> +     ret = devm_clk_hw_register(rpi->dev, &rpi->pllb);
> +     if (!ret)
> +             clk_hw_set_rate_range(&rpi->pllb,
> +                                   min_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE,
> +                                   max_rate *
> RPI_FIRMWARE_PLLB_ARM_DIV_RATE);

Isn't there a potential race here? Albeit unlikely, cpufreq could show up and
call clk_round_rate() in between the registration and you setting the ranges.

Regards,
Nicolas


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