Remi Pommarel <r...@triplefau.lt> writes:
> Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor
> so that the resulting average rate will not be higher than the requested one.
>
> Signed-off-by: Remi Pommarel <r...@triplefau.lt>
> ---
> drivers/clk/bcm/clk-bcm2835.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
> index 39bf582..9e881ee 100644
> --- a/drivers/clk/bcm/clk-bcm2835.c
> +++ b/drivers/clk/bcm/clk-bcm2835.c
> @@ -1148,22 +1148,24 @@ static int bcm2835_clock_is_on(struct clk_hw *hw)
>
> static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
> unsigned long rate,
> - unsigned long parent_rate)
> + unsigned long parent_rate,
> + bool round_up)
> {
> struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
> const struct bcm2835_clock_data *data = clock->data;
> - u32 unused_frac_mask = GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0);
> + u32 unused_frac_mask =
> + GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1;
> u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS;
> + u64 rem;
> u32 div;
>
> - do_div(temp, rate);
> + rem = do_div(temp, rate);
> div = temp;
>
> - /* Round and mask off the unused bits */
> - if (unused_frac_mask != 0) {
> - div += unused_frac_mask >> 1;
> - div &= ~unused_frac_mask;
> - }
> + /* Round up and mask off the unused bits */
> + if (round_up && ((div & unused_frac_mask) != 0 || rem != 0))
> + div += unused_frac_mask + 1;
> + div &= ~unused_frac_mask;
>
> /* Clamp to the limits. */
> div = max(div, unused_frac_mask + 1);
> @@ -1202,7 +1204,7 @@ static long bcm2835_clock_round_rate(struct clk_hw *hw,
> unsigned long *parent_rate)
> {
> struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw);
> - u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate);
> + u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate, false);
>
> return bcm2835_clock_rate_from_divisor(clock, *parent_rate, div);
> }
> @@ -1271,7 +1273,7 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw,
> struct bcm2835_clock *clock = bcm2835_clock_from_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);
> + u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);I think you meant ", true" on one of these. With that fixed, Reviewed-by: Eric Anholt <e...@anholt.net>
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