[PATCH 5/5] OMAP2+: clock: remove the DPLL rate tolerance code
Paul Walmsley
paul at pwsan.com
Wed Feb 16 23:17:56 EST 2011
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 <paul at pwsan.com>
---
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 337392c..17735e7 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)
@@ -260,50 +259,22 @@ 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 70f8b07..62cfd6c 100644
--- a/arch/arm/mach-omap2/clock.h
+++ b/arch/arm/mach-omap2/clock.h
@@ -18,9 +18,6 @@
#include <plat/clock.h>
-/* 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 6e9d20d..22eeafc 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 3378dbf..df4cac5 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 58db368..b82afec 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 48b52fb..072eef1 100644
--- a/arch/arm/plat-omap/include/plat/clock.h
+++ b/arch/arm/plat-omap/include/plat/clock.h
@@ -108,7 +108,6 @@ 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)
@@ -134,12 +133,9 @@ 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 {
@@ -150,7 +146,6 @@ 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;
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