From: Baruch Siach <baruch@tkos.co.il> To: "Thierry Reding" <thierry.reding@gmail.com>, "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>, "Lee Jones" <lee.jones@linaro.org>, "Linus Walleij" <linus.walleij@linaro.org>, "Bartosz Golaszewski" <bgolaszewski@baylibre.com> Cc: Baruch Siach <baruch@tkos.co.il>, Andrew Lunn <andrew@lunn.ch>, Gregory Clement <gregory.clement@bootlin.com>, Russell King <linux@armlinux.org.uk>, Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>, Thomas Petazzoni <thomas.petazzoni@bootlin.com>, Chris Packham <chris.packham@alliedtelesis.co.nz>, Sascha Hauer <s.hauer@pengutronix.de>, Ralph Sennhauser <ralph.sennhauser@gmail.com>, linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy Date: Wed, 20 Jan 2021 18:16:25 +0200 [thread overview] Message-ID: <0c70e683121eb6970cfce31aa105cd09d52297e6.1611128398.git.baruch@tkos.co.il> (raw) In-Reply-To: <cover.1611128398.git.baruch@tkos.co.il> Change 'off' register value calculation from $off = (period - duty_cycle) * clkrate / NSEC_PER_SEC to $off = (period * clkrate / NSEC_PER_SEC) - $on That is, divide the full period value to reduce rounding error. Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Baruch Siach <baruch@tkos.co.il> --- drivers/gpio/gpio-mvebu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index a912a8fed197..c424d88e9e2b 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, else on = 1; - val = (unsigned long long) mvpwm->clk_rate * - (state->period - state->duty_cycle); + val = (unsigned long long) mvpwm->clk_rate * state->period; do_div(val, NSEC_PER_SEC); + val -= on; if (val > UINT_MAX) return -EINVAL; if (val) -- 2.29.2
WARNING: multiple messages have this Message-ID (diff)
From: Baruch Siach <baruch@tkos.co.il> To: "Thierry Reding" <thierry.reding@gmail.com>, "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>, "Lee Jones" <lee.jones@linaro.org>, "Linus Walleij" <linus.walleij@linaro.org>, "Bartosz Golaszewski" <bgolaszewski@baylibre.com> Cc: Andrew Lunn <andrew@lunn.ch>, Baruch Siach <baruch@tkos.co.il>, linux-pwm@vger.kernel.org, Gregory Clement <gregory.clement@bootlin.com>, Russell King <linux@armlinux.org.uk>, linux-gpio@vger.kernel.org, Chris Packham <chris.packham@alliedtelesis.co.nz>, Thomas Petazzoni <thomas.petazzoni@bootlin.com>, Ralph Sennhauser <ralph.sennhauser@gmail.com>, Sascha Hauer <s.hauer@pengutronix.de>, linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> Subject: [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy Date: Wed, 20 Jan 2021 18:16:25 +0200 [thread overview] Message-ID: <0c70e683121eb6970cfce31aa105cd09d52297e6.1611128398.git.baruch@tkos.co.il> (raw) In-Reply-To: <cover.1611128398.git.baruch@tkos.co.il> Change 'off' register value calculation from $off = (period - duty_cycle) * clkrate / NSEC_PER_SEC to $off = (period * clkrate / NSEC_PER_SEC) - $on That is, divide the full period value to reduce rounding error. Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Baruch Siach <baruch@tkos.co.il> --- drivers/gpio/gpio-mvebu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index a912a8fed197..c424d88e9e2b 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -715,9 +715,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, else on = 1; - val = (unsigned long long) mvpwm->clk_rate * - (state->period - state->duty_cycle); + val = (unsigned long long) mvpwm->clk_rate * state->period; do_div(val, NSEC_PER_SEC); + val -= on; if (val > UINT_MAX) return -EINVAL; if (val) -- 2.29.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-01-20 16:19 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-20 16:16 [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements Baruch Siach 2021-01-20 16:16 ` Baruch Siach 2021-01-20 16:16 ` Baruch Siach [this message] 2021-01-20 16:16 ` [PATCH v5 1/4] gpio: mvebu: improve pwm period calculation accuracy Baruch Siach 2021-01-20 16:16 ` [PATCH v5 2/4] gpio: mvebu: make pwm .get_state closer to idempotent Baruch Siach 2021-01-20 16:16 ` Baruch Siach 2021-01-20 16:16 ` [PATCH v5 3/4] gpio: mvebu: don't limit pwm period/duty_cycle to UINT_MAX Baruch Siach 2021-01-20 16:16 ` Baruch Siach 2021-01-20 16:16 ` [PATCH v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values Baruch Siach 2021-01-20 16:16 ` Baruch Siach 2021-01-20 17:24 ` Uwe Kleine-König 2021-01-20 17:24 ` Uwe Kleine-König 2021-01-25 9:43 ` [PATCH v5 0/4] gpio: mvebu: pwm fixes and improvements Bartosz Golaszewski 2021-01-25 9:43 ` Bartosz Golaszewski
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