Messages in this thread | | | Date | Fri, 23 May 2014 18:24:31 -0500 | From | Alex Elder <> | Subject | Re: [PATCH] clk: bcm/kona: implement determine_rate() |
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On 05/23/2014 06:18 PM, Mike Turquette wrote: > Quoting Alex Elder (2014-05-20 06:24:57) >> Implement the clk->determine_rate method for Broadcom Kona peripheral >> clocks. This allows a peripheral clock to be re-parented in order to >> satisfy a rate change request. This takes the place of the previous >> kona_peri_clk_round_rate() functionality, though that function remains >> because it is used by the new one. >> >> The parent clock that allows the peripheral clock to produce a rate >> closest to the one requested is the one selected, though the current >> parent is used by default. >> >> Signed-off-by: Alex Elder <elder@linaro.org> >> --- >> This patch is based on Mike Turquette's current "clk-next" branch. >> 6ed8eb5 Merge tag 'clk-hisi-for-v3.16' of https://git.kern... >> >> It is available here: >> http://git.linaro.org/landing-teams/working/broadcom/kernel.git >> Branch review/bcm-determine-rate >> >> drivers/clk/bcm/clk-kona.c | 53 +++++++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 52 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c >> index d603c4e..1a4eccc 100644 >> --- a/drivers/clk/bcm/clk-kona.c >> +++ b/drivers/clk/bcm/clk-kona.c >> @@ -1031,6 +1031,57 @@ static long kona_peri_clk_round_rate(struct clk_hw *hw, unsigned long rate, >> rate ? rate : 1, *parent_rate, NULL); >> } >> >> +static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate, >> + unsigned long *best_parent_rate, struct clk **best_parent) >> +{ >> + struct kona_clk *bcm_clk = to_kona_clk(hw); >> + struct clk *clk = hw->clk; >> + struct clk *current_parent; >> + unsigned long parent_rate; >> + unsigned long best_delta; >> + unsigned long best_rate; >> + u32 parent_count; >> + u32 which; >> + >> + /* >> + * If there is no other parent to choose, use the current one. >> + * Note: We don't honor (or use) CLK_SET_RATE_NO_REPARENT. >> + */ > > A WARN_ONCE is appropriate upon detection of CLK_SET_RATE_NO_REPARENT. > It will certainly help someone that is debugging why that flag has no > effect.
I'll add that.
> Otherwise the patch looks good to me.
Would you like me to send an updated patch as a pull request?
Thanks.
-Alex
> Regards, > Mike > >> + parent_count = (u32)bcm_clk->init_data.num_parents; >> + if (parent_count < 2) >> + return kona_peri_clk_round_rate(hw, rate, best_parent_rate); >> + >> + /* Unless we can do better, stick with current parent */ >> + current_parent = clk_get_parent(clk); >> + parent_rate = __clk_get_rate(current_parent); >> + best_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate); >> + best_delta = abs(best_rate - rate); >> + >> + /* Check whether any other parent clock can produce a better result */ >> + for (which = 0; which < parent_count; which++) { >> + struct clk *parent = clk_get_parent_by_index(clk, which); >> + unsigned long delta; >> + unsigned long other_rate; >> + >> + BUG_ON(!parent); >> + if (parent == current_parent) >> + continue; >> + >> + /* We don't support CLK_SET_RATE_PARENT */ >> + parent_rate = __clk_get_rate(parent); >> + other_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate); >> + delta = abs(other_rate - rate); >> + if (delta < best_delta) { >> + best_delta = delta; >> + best_rate = other_rate; >> + *best_parent = parent; >> + *best_parent_rate = parent_rate; >> + } >> + } >> + >> + return best_rate; >> +} >> + >> static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index) >> { >> struct kona_clk *bcm_clk = to_kona_clk(hw); >> @@ -1135,7 +1186,7 @@ struct clk_ops kona_peri_clk_ops = { >> .disable = kona_peri_clk_disable, >> .is_enabled = kona_peri_clk_is_enabled, >> .recalc_rate = kona_peri_clk_recalc_rate, >> - .round_rate = kona_peri_clk_round_rate, >> + .determine_rate = kona_peri_clk_determine_rate, >> .set_parent = kona_peri_clk_set_parent, >> .get_parent = kona_peri_clk_get_parent, >> .set_rate = kona_peri_clk_set_rate, >> -- >> 1.9.1 >>
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