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From: Roman Beranek <roman.beranek@prusa3d.cz>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Emil Lenngren <emil.lenngren@gmail.com>,
	Pascal Roeleven <dev@pascalroeleven.nl>,
	Lee Jones <lee.jones@linaro.org>,
	Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, linux-sunxi@googlegroups.com
Subject: [PATCH 0/6] pwm: sun4i: only wait 2 cycles prior to disabling
Date: Mon, 31 May 2021 06:46:02 +0200	[thread overview]
Message-ID: <20210531044608.1006024-1-roman.beranek@prusa3d.com> (raw)

As Emil Lenngren has previously shown [1], actually only 1-2 cycles of
the prescaler-divided clock are necessary to pass before the PWM turns
off, not a full period.

To avoid having the PWM re-enabled from another thread while asleep,
ctrl_lock spinlock was converted to a mutex so that it can be released
only after the clock gate has finally been turned on.

[1] https://linux-sunxi.org/PWM_Controller_Register_Guide

Roman Beranek (6):
  pwm: sun4i: enable clk prior to getting its rate
  pwm: sun4i: disable EN bit prior to the delay
  pwm: sun4i: replace spinlock with a mutex
  pwm: sun4i: simplify calculation of the delay time
  pwm: sun4i: shorten the delay to 2 cycles
  pwm: sun4i: don't delay if the PWM is already off

 drivers/pwm/pwm-sun4i.c | 56 +++++++++++++++++++----------------------
 1 file changed, 26 insertions(+), 30 deletions(-)

-- 
2.31.1


             reply	other threads:[~2021-05-31  4:46 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-31  4:46 Roman Beranek [this message]
2021-05-31  4:46 ` [PATCH 1/6] pwm: sun4i: enable clk prior to getting its rate Roman Beranek
2021-06-07  8:00   ` Uwe Kleine-König
2021-05-31  4:46 ` [PATCH 2/6] pwm: sun4i: disable EN bit prior to the delay Roman Beranek
2021-06-07  8:07   ` Uwe Kleine-König
2021-05-31  4:46 ` [PATCH 3/6] pwm: sun4i: replace spinlock with a mutex Roman Beranek
2021-05-31  4:46 ` [PATCH 4/6] pwm: sun4i: simplify calculation of the delay time Roman Beranek
2021-05-31  4:46 ` [PATCH 5/6] pwm: sun4i: shorten the delay to 2 cycles Roman Beranek
2021-05-31  4:46 ` [PATCH 6/6] pwm: sun4i: don't delay if the PWM is already off Roman Beranek
2021-06-10 13:41   ` Pascal Roeleven
2021-05-31 19:07 ` [PATCH 0/6] pwm: sun4i: only wait 2 cycles prior to disabling Pascal Roeleven
2021-05-31 20:01   ` Emil Lenngren
2021-05-31 20:20     ` Pascal Roeleven
2021-06-08 12:28   ` Pascal Roeleven

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