From 241d3a8dca239610d3d991bf58d4fe38c2d86fd5 Mon Sep 17 00:00:00 2001 From: Paul Walmsley Date: Wed, 16 Feb 2011 15:38:39 -0700 Subject: [PATCH] OMAP2+: clock: remove the DPLL rate tolerance code Remove the DPLL rate tolerance code that is called during rate rounding. As far as I know, this code is never used, since it's been more important for callers of the DPLL round_rate()/set_rate() functions to obtain an exact rate than it is to save a relatively small amount of power. Signed-off-by: Paul Walmsley --- arch/arm/mach-omap2/clkt_dpll.c | 91 +++++++------------------ arch/arm/mach-omap2/clock.h | 4 -- arch/arm/mach-omap2/clock2420_data.c | 1 - arch/arm/mach-omap2/clock2430_data.c | 1 - arch/arm/mach-omap2/clock3xxx_data.c | 6 -- arch/arm/plat-omap/include/plat/clock.h | 7 +- 6 files changed, 24 insertions(+), 86 deletions(-) diff --git a/arch/arm/mach-omap2/clkt_dpll.c b/arch/arm/mach-omap2/clkt_dpll.c index 337392c3f549..17735e7f47b1 100644 --- a/arch/arm/mach-omap2/clkt_dpll.c +++ b/arch/arm/mach-omap2/clkt_dpll.c @@ -178,12 +178,11 @@ void omap2_init_dpll_parent(struct clk *clk) if (!dd) return; - /* Return bypass rate if DPLL is bypassed */ v = __raw_readl(dd->control_reg); v &= dd->enable_mask; v >>= __ffs(dd->enable_mask); - /* Reparent in case the dpll is in bypass */ + /* Reparent the struct clk in case the dpll is in bypass */ if (cpu_is_omap24xx()) { if (v == OMAP2XXX_EN_DPLL_LPBYPASS || v == OMAP2XXX_EN_DPLL_FRBYPASS) @@ -259,51 +258,23 @@ u32 omap2_get_dpll_rate(struct clk *clk) /* DPLL rate rounding code */ -/** - * omap2_dpll_set_rate_tolerance: set the error tolerance during rate rounding - * @clk: struct clk * of the DPLL - * @tolerance: maximum rate error tolerance - * - * Set the maximum DPLL rate error tolerance for the rate rounding - * algorithm. The rate tolerance is an attempt to balance DPLL power - * saving (the least divider value "n") vs. rate fidelity (the least - * difference between the desired DPLL target rate and the rounded - * rate out of the algorithm). So, increasing the tolerance is likely - * to decrease DPLL power consumption and increase DPLL rate error. - * Returns -EINVAL if provided a null clock ptr or a clk that is not a - * DPLL; or 0 upon success. - */ -int omap2_dpll_set_rate_tolerance(struct clk *clk, unsigned int tolerance) -{ - if (!clk || !clk->dpll_data) - return -EINVAL; - - clk->dpll_data->rate_tolerance = tolerance; - - return 0; -} - /** * omap2_dpll_round_rate - round a target rate for an OMAP DPLL * @clk: struct clk * for a DPLL * @target_rate: desired DPLL clock rate * - * Given a DPLL, a desired target rate, and a rate tolerance, round - * the target rate to a possible, programmable rate for this DPLL. - * Rate tolerance is assumed to be set by the caller before this - * function is called. Attempts to select the minimum possible n - * within the tolerance to reduce power consumption. Stores the - * computed (m, n) in the DPLL's dpll_data structure so set_rate() - * will not need to call this (expensive) function again. Returns ~0 - * if the target rate cannot be rounded, either because the rate is - * too low or because the rate tolerance is set too tightly; or the - * rounded rate upon success. + * Given a DPLL and a desired target rate, round the target rate to a + * possible, programmable rate for this DPLL. Attempts to select the + * minimum possible n. Stores the computed (m, n) in the DPLL's + * dpll_data structure so set_rate() will not need to call this + * (expensive) function again. Returns ~0 if the target rate cannot + * be rounded, or the rounded rate upon success. */ long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate) { - int m, n, r, e, scaled_max_m; - unsigned long scaled_rt_rp, new_rate; - int min_e = -1, min_e_m = -1, min_e_n = -1; + int m, n, r, scaled_max_m; + unsigned long scaled_rt_rp; + unsigned long new_rate = 0; struct dpll_data *dd; if (!clk || !clk->dpll_data) @@ -311,8 +282,8 @@ long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate) dd = clk->dpll_data; - pr_debug("clock: starting DPLL round_rate for clock %s, target rate " - "%ld\n", clk->name, target_rate); + pr_debug("clock: %s: starting DPLL round_rate, target rate %ld\n", + clk->name, target_rate); scaled_rt_rp = target_rate / (dd->clk_ref->rate / DPLL_SCALE_FACTOR); scaled_max_m = dd->max_multiplier * DPLL_SCALE_FACTOR; @@ -347,39 +318,23 @@ long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate) if (r == DPLL_MULT_UNDERFLOW) continue; - e = target_rate - new_rate; - pr_debug("clock: n = %d: m = %d: rate error is %d " - "(new_rate = %ld)\n", n, m, e, new_rate); - - if (min_e == -1 || - min_e >= (int)(abs(e) - dd->rate_tolerance)) { - min_e = e; - min_e_m = m; - min_e_n = n; - - pr_debug("clock: found new least error %d\n", min_e); + pr_debug("clock: %s: m = %d: n = %d: new_rate = %ld\n", + clk->name, m, n, new_rate); - /* We found good settings -- bail out now */ - if (min_e <= dd->rate_tolerance) - break; + if (target_rate == new_rate) { + dd->last_rounded_m = m; + dd->last_rounded_n = n; + dd->last_rounded_rate = target_rate; + break; } } - if (min_e < 0) { - pr_debug("clock: error: target rate or tolerance too low\n"); + if (target_rate != new_rate) { + pr_debug("clock: %s: cannot round to rate %ld\n", clk->name, + target_rate); return ~0; } - dd->last_rounded_m = min_e_m; - dd->last_rounded_n = min_e_n; - dd->last_rounded_rate = _dpll_compute_new_rate(dd->clk_ref->rate, - min_e_m, min_e_n); - - pr_debug("clock: final least error: e = %d, m = %d, n = %d\n", - min_e, min_e_m, min_e_n); - pr_debug("clock: final rate: %ld (target rate: %ld)\n", - dd->last_rounded_rate, target_rate); - - return dd->last_rounded_rate; + return target_rate; } diff --git a/arch/arm/mach-omap2/clock.h b/arch/arm/mach-omap2/clock.h index 70f8b073e69f..62cfd6cc7461 100644 --- a/arch/arm/mach-omap2/clock.h +++ b/arch/arm/mach-omap2/clock.h @@ -18,9 +18,6 @@ #include -/* The maximum error between a target DPLL rate and the rounded rate in Hz */ -#define DEFAULT_DPLL_RATE_TOLERANCE 50000 - /* CM_CLKSEL2_PLL.CORE_CLK_SRC bits (2XXX) */ #define CORE_CLK_SRC_32K 0x0 #define CORE_CLK_SRC_DPLL 0x1 @@ -55,7 +52,6 @@ void omap2_clk_disable(struct clk *clk); long omap2_clk_round_rate(struct clk *clk, unsigned long rate); int omap2_clk_set_rate(struct clk *clk, unsigned long rate); int omap2_clk_set_parent(struct clk *clk, struct clk *new_parent); -int omap2_dpll_set_rate_tolerance(struct clk *clk, unsigned int tolerance); long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate); unsigned long omap3_dpll_recalc(struct clk *clk); unsigned long omap3_clkoutx2_recalc(struct clk *clk); diff --git a/arch/arm/mach-omap2/clock2420_data.c b/arch/arm/mach-omap2/clock2420_data.c index 6e9d20dc8649..22eeafc89b9f 100644 --- a/arch/arm/mach-omap2/clock2420_data.c +++ b/arch/arm/mach-omap2/clock2420_data.c @@ -116,7 +116,6 @@ static struct dpll_data dpll_dd = { .max_multiplier = 1023, .min_divider = 1, .max_divider = 16, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; /* diff --git a/arch/arm/mach-omap2/clock2430_data.c b/arch/arm/mach-omap2/clock2430_data.c index 3378dbf8bace..df4cac5fef06 100644 --- a/arch/arm/mach-omap2/clock2430_data.c +++ b/arch/arm/mach-omap2/clock2430_data.c @@ -116,7 +116,6 @@ static struct dpll_data dpll_dd = { .max_multiplier = 1023, .min_divider = 1, .max_divider = 16, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; /* diff --git a/arch/arm/mach-omap2/clock3xxx_data.c b/arch/arm/mach-omap2/clock3xxx_data.c index 305b5f75c44f..3dbeb3a5813d 100644 --- a/arch/arm/mach-omap2/clock3xxx_data.c +++ b/arch/arm/mach-omap2/clock3xxx_data.c @@ -291,7 +291,6 @@ static struct dpll_data dpll1_dd = { .max_multiplier = OMAP3_MAX_DPLL_MULT, .min_divider = 1, .max_divider = OMAP3_MAX_DPLL_DIV, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; static struct clk dpll1_ck = { @@ -364,7 +363,6 @@ static struct dpll_data dpll2_dd = { .max_multiplier = OMAP3_MAX_DPLL_MULT, .min_divider = 1, .max_divider = OMAP3_MAX_DPLL_DIV, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; static struct clk dpll2_ck = { @@ -424,7 +422,6 @@ static struct dpll_data dpll3_dd = { .max_multiplier = OMAP3_MAX_DPLL_MULT, .min_divider = 1, .max_divider = OMAP3_MAX_DPLL_DIV, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; static struct clk dpll3_ck = { @@ -583,7 +580,6 @@ static struct dpll_data dpll4_dd_34xx __initdata = { .max_multiplier = OMAP3_MAX_DPLL_MULT, .min_divider = 1, .max_divider = OMAP3_MAX_DPLL_DIV, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; static struct dpll_data dpll4_dd_3630 __initdata = { @@ -607,7 +603,6 @@ static struct dpll_data dpll4_dd_3630 __initdata = { .max_multiplier = OMAP3630_MAX_JTYPE_DPLL_MULT, .min_divider = 1, .max_divider = OMAP3_MAX_DPLL_DIV, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE, .flags = DPLL_J_TYPE }; @@ -939,7 +934,6 @@ static struct dpll_data dpll5_dd = { .max_multiplier = OMAP3_MAX_DPLL_MULT, .min_divider = 1, .max_divider = OMAP3_MAX_DPLL_DIV, - .rate_tolerance = DEFAULT_DPLL_RATE_TOLERANCE }; static struct clk dpll5_ck = { diff --git a/arch/arm/plat-omap/include/plat/clock.h b/arch/arm/plat-omap/include/plat/clock.h index dcd7bb81420d..006e599c6613 100644 --- a/arch/arm/plat-omap/include/plat/clock.h +++ b/arch/arm/plat-omap/include/plat/clock.h @@ -109,7 +109,6 @@ struct clksel { * @clk_ref: struct clk pointer to the clock's reference clock input * @control_reg: register containing the DPLL mode bitfield * @enable_mask: mask of the DPLL mode bitfield in @control_reg - * @rate_tolerance: maximum variance allowed from target rate (in Hz) * @last_rounded_rate: cache of the last rate result of omap2_dpll_round_rate() * @last_rounded_m: cache of the last M result of omap2_dpll_round_rate() * @max_multiplier: maximum valid non-bypass multiplier value (actual) @@ -135,12 +134,9 @@ struct clksel { * XXX Some DPLLs have multiple bypass inputs, so it's not technically * correct to only have one @clk_bypass pointer. * - * XXX @rate_tolerance should probably be deprecated - currently there - * don't seem to be any usecases for DPLL rounding that is not exact. - * * XXX The runtime-variable fields (@last_rounded_rate, @last_rounded_m, * @last_rounded_n) should be separated from the runtime-fixed fields - * and placed into a differenct structure, so that the runtime-fixed data + * and placed into a different structure, so that the runtime-fixed data * can be placed into read-only space. */ struct dpll_data { @@ -151,7 +147,6 @@ struct dpll_data { struct clk *clk_ref; void __iomem *control_reg; u32 enable_mask; - unsigned int rate_tolerance; unsigned long last_rounded_rate; u16 last_rounded_m; u16 max_multiplier; -- 2.39.2