From 5517357a4733d7cf7c17fc79d0530cfa47add372 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Wed, 22 Sep 2021 14:54:15 +0200 Subject: clk: bcm-2835: Pick the closest clock rate The driver currently tries to pick the closest rate that is lower than the rate being requested. This causes an issue with clk_set_min_rate() since it actively checks for the rounded rate to be above the minimum that was just set. Let's change the logic a bit to pick the closest rate to the requested rate, no matter if it's actually higher or lower. Fixes: 6d18b8adbe67 ("clk: bcm2835: Support for clock parent selection") Signed-off-by: Maxime Ripard Acked-by: Stephen Boyd Reviewed-by: Nicolas Saenz Julienne Tested-by: Nicolas Saenz Julienne # boot and basic functionality Tested-by: Michael Stapelberg Link: https://patchwork.freedesktop.org/patch/msgid/20210922125419.4125779-2-maxime@cerno.tech --- drivers/clk/bcm/clk-bcm2835.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/clk') diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c index a254512965eb..bf97b2b2a63f 100644 --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c @@ -1216,7 +1216,7 @@ static int bcm2835_clock_determine_rate(struct clk_hw *hw, rate = bcm2835_clock_choose_div_and_prate(hw, i, req->rate, &div, &prate, &avgrate); - if (rate > best_rate && rate <= req->rate) { + if (abs(req->rate - rate) < abs(req->rate - best_rate)) { best_parent = parent; best_prate = prate; best_rate = rate; -- cgit v1.2.3-59-g8ed1b From 8ca011ef4af48a7af7b15afd8a4a44039dd04cea Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Wed, 22 Sep 2021 14:54:16 +0200 Subject: clk: bcm-2835: Remove rounding up the dividers The driver, once it found a divider, tries to round it up by increasing the least significant bit of the fractional part by one when the round_up argument is set and there's a remainder. However, since it increases the divider it will actually reduce the clock rate below what we were asking for, leading to issues with clk_set_min_rate() that will complain that our rounded clock rate is below the minimum of the rate. Since the dividers are fairly precise already, let's remove that part so that we can have clk_set_min_rate() working. This is effectively a revert of 9c95b32ca093 ("clk: bcm2835: add a round up ability to the clock divisor"). Fixes: 9c95b32ca093 ("clk: bcm2835: add a round up ability to the clock divisor") Signed-off-by: Maxime Ripard Acked-by: Stephen Boyd Reviewed-by: Nicolas Saenz Julienne Tested-by: Nicolas Saenz Julienne # boot and basic functionality Tested-by: Michael Stapelberg Link: https://patchwork.freedesktop.org/patch/msgid/20210922125419.4125779-3-maxime@cerno.tech --- drivers/clk/bcm/clk-bcm2835.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) (limited to 'drivers/clk') diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c index bf97b2b2a63f..3667b4d731e7 100644 --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c @@ -932,8 +932,7 @@ 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, - bool round_up) + unsigned long parent_rate) { struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw); const struct bcm2835_clock_data *data = clock->data; @@ -945,10 +944,6 @@ static u32 bcm2835_clock_choose_div(struct clk_hw *hw, rem = do_div(temp, rate); div = temp; - - /* 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; /* different clamping limits apply for a mash clock */ @@ -1079,7 +1074,7 @@ 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, false); + u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate); u32 ctl; spin_lock(&cprman->regs_lock); @@ -1130,7 +1125,7 @@ static unsigned long bcm2835_clock_choose_div_and_prate(struct clk_hw *hw, if (!(BIT(parent_idx) & data->set_rate_parent)) { *prate = clk_hw_get_rate(parent); - *div = bcm2835_clock_choose_div(hw, rate, *prate, true); + *div = bcm2835_clock_choose_div(hw, rate, *prate); *avgrate = bcm2835_clock_rate_from_divisor(clock, *prate, *div); -- cgit v1.2.3-59-g8ed1b