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From: Paul Cercueil <paul@crapouillou.net>
To: "Thierry Reding" <thierry.reding@gmail.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Daniel Lezcano" <daniel.lezcano@linaro.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ralf Baechle" <ralf@linux-mips.org>,
	"Paul Burton" <paul.burton@mips.com>,
	"James Hogan" <jhogan@kernel.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-clk@vger.kernel.org, Paul Cercueil <paul@crapouillou.net>
Subject: [PATCH v9 14/27] pwm: jz4740: Improve algorithm of clock calculation
Date: Thu, 27 Dec 2018 19:13:06 +0100	[thread overview]
Message-ID: <20181227181319.31095-15-paul@crapouillou.net> (raw)
In-Reply-To: <20181227181319.31095-1-paul@crapouillou.net>

The previous algorithm hardcoded details about how the TCU clocks work.
The new algorithm will use clk_round_rate to find the perfect clock rate
for the PWM channel.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---

Notes:
     v9: New patch

 drivers/pwm/pwm-jz4740.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index c6136bd4434b..dd80a2cf6528 100644
--- a/drivers/pwm/pwm-jz4740.c
+++ b/drivers/pwm/pwm-jz4740.c
@@ -110,23 +110,27 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
 	struct clk *clk = jz4740->clks[pwm->hwpwm],
 		   *parent_clk = clk_get_parent(clk);
-	unsigned long rate, period, duty;
+	unsigned long rate, new_rate, period, duty;
 	unsigned long long tmp;
-	unsigned int prescaler = 0;
 
 	rate = clk_get_rate(parent_clk);
-	tmp = (unsigned long long)rate * state->period;
-	do_div(tmp, 1000000000);
-	period = tmp;
 
-	while (period > 0xffff && prescaler < 6) {
-		period >>= 2;
-		rate >>= 2;
-		++prescaler;
+	for (;;) {
+		tmp = (unsigned long long)rate * state->period;
+		do_div(tmp, 1000000000);
+
+		if (tmp <= 0xffff)
+			break;
+
+		new_rate = clk_round_rate(clk, rate - 1);
+
+		if (new_rate < rate)
+			rate = new_rate;
+		else
+			return -EINVAL;
 	}
 
-	if (prescaler == 6)
-		return -EINVAL;
+	period = tmp;
 
 	tmp = (unsigned long long)period * state->duty_cycle;
 	do_div(tmp, state->period);
-- 
2.11.0


  parent reply	other threads:[~2018-12-27 18:15 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-27 18:12 [PATCH v9 00/27] Ingenic TCU patchset v9 Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 01/27] dt-bindings: ingenic: Add DT bindings for TCU clocks Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 02/27] doc: Add doc for the Ingenic TCU hardware Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 03/27] dt-bindings: Add doc for the Ingenic TCU drivers Paul Cercueil
2018-12-28 21:48   ` Rob Herring
2018-12-27 18:12 ` [PATCH v9 04/27] clocksource: Add a new timer-ingenic driver Paul Cercueil
2019-02-25 15:55   ` Daniel Lezcano
2019-02-25 22:59     ` Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 05/27] clocksource: Add driver for the Ingenic JZ47xx OST Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 06/27] MAINTAINERS: Add myself as maintainer for Ingenic TCU drivers Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 07/27] watchdog: jz4740: Use WDT clock provided by TCU driver Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 08/27] watchdog: jz4740: Use regmap " Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 09/27] watchdog: jz4740: Avoid starting watchdog in set_timeout Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 10/27] watchdog: jz4740: Drop dependency on MACH_JZ47xx, use COMPILE_TEST Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 11/27] pwm: jz4740: Apply configuration atomically Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 12/27] pwm: jz4740: Use regmap from TCU driver Paul Cercueil
2019-01-05 19:42   ` Uwe Kleine-König
2019-01-05 20:46     ` Paul Cercueil
2019-01-05 21:18       ` Uwe Kleine-König
2018-12-27 18:13 ` [PATCH v9 13/27] pwm: jz4740: Use clocks " Paul Cercueil
2019-01-05 19:45   ` Uwe Kleine-König
2019-01-05 20:52     ` Paul Cercueil
2019-01-05 21:19       ` Uwe Kleine-König
2018-12-27 18:13 ` Paul Cercueil [this message]
2019-01-05 19:57   ` [PATCH v9 14/27] pwm: jz4740: Improve algorithm of clock calculation Uwe Kleine-König
2019-01-05 21:05     ` Paul Cercueil
2019-01-05 21:27       ` Uwe Kleine-König
2019-01-10 14:04         ` Paul Cercueil
2019-02-23  1:17           ` Paul Cercueil
2019-02-28 18:42             ` Stephen Boyd
2018-12-27 18:13 ` [PATCH v9 15/27] pwm: jz4740: Allow selection of PWM channels 0 and 1 Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 16/27] pwm: jz4740: Drop dependency on MACH_INGENIC, use COMPILE_TEST Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 17/27] pwm: jz4740: Remove unused devicetree compatible strings Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 18/27] clk: jz4740: Add TCU clock Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 19/27] MIPS: Kconfig: Select TCU timer driver when MACH_INGENIC is set Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 20/27] MIPS: jz4740: Add DTS nodes for the TCU drivers Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 21/27] MIPS: qi_lb60: Move PWM devices to devicetree Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 22/27] MIPS: qi_lb60: Reduce system timer and clocksource to 750 kHz Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 23/27] MIPS: CI20: Reduce system timer to 3 MHz Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 24/27] MIPS: CI20: defconfig: enable OST driver Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 25/27] MIPS: GCW0: Reduce system timer to 750 kHz Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 26/27] MIPS: GCW0: defconfig: Enable OST, watchdog, PWM drivers Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 27/27] MIPS: jz4740: Drop obsolete code Paul Cercueil

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