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8035e6c66a
linux/drivers/pwm
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Uwe Kleine-König 8035e6c66a pwm: atmel: Improve duty cycle calculation in .apply() 
In the calculation of the register value determining the duty cycle the
requested period is used instead of the actually implemented period which
results in suboptimal settings.

The following example assumes an input clock of 133333333 Hz on one of
the SoCs with 16 bit period.

When the following state is to be applied:

        .period = 414727681
        .duty_cycle = 652806

the following register values used to be  calculated:

        PRES = 10
        CPRD = 54000
        CDTY = 53916

which yields an actual duty cycle of a bit more than 645120 ns.

The setting

        PRES = 10
        CPRD = 54000
        CDTY = 53915

however yields a duty of 652800 ns which is between the current result
and the requested value and so is a better approximation.

The reason for this error is that for the calculation of CDTY the
requested period was used instead of the actually implemented one.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2021-04-23 19:05:31 +02:00
..
core.c pwm: Drop function pwmchip_add_with_polarity() 2021-03-22 12:31:32 +01:00
Kconfig pwm: visconti: Add Toshiba Visconti SoC PWM support 2021-04-23 19:05:13 +02:00
Makefile pwm: visconti: Add Toshiba Visconti SoC PWM support 2021-04-23 19:05:13 +02:00
pwm-ab8500.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-atmel-hlcdc.c pwm: atmel-hlcdc: Use pwmchip_add() instead of pwmchip_add_with_polarity() 2021-03-22 12:19:08 +01:00
pwm-atmel-tcb.c pwm: atmel-tcb: Only free resources after pwm_chip_remove() returned 2021-03-22 12:06:45 +01:00
pwm-atmel.c pwm: atmel: Improve duty cycle calculation in .apply() 2021-04-23 19:05:31 +02:00
pwm-bcm2835.c pwm: bcm2835: Free resources only after pwmchip_remove() 2021-04-09 14:33:39 +02:00
pwm-bcm-iproc.c pwm: bcm-iproc: Free resources only after pwmchip_remove() 2021-04-09 14:33:10 +02:00
pwm-bcm-kona.c pwm: bcm-kona: Don't modify HW state in .remove callback 2021-04-09 14:44:12 +02:00
pwm-berlin.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-brcmstb.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-clps711x.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-crc.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-cros-ec.c pwm: cros-ec: Refuse requests with unsupported polarity 2021-03-22 12:08:06 +01:00
pwm-dwc.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-ep93xx.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-fsl-ftm.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-hibvt.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-img.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-imx1.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-imx27.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-imx-tpm.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-intel-lgm.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-iqs620a.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-jz4740.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-keembay.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-lp3943.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-lpc18xx-sct.c pwm: lpc18xx-sct: Free resources only after pwmchip_remove() 2021-04-09 14:44:37 +02:00
pwm-lpc32xx.c pwm: lpc3200: Don't modify HW state in .remove callback 2021-04-09 14:45:11 +02:00
pwm-lpss-pci.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
pwm-lpss-platform.c pwm: lpss: Set DPM_FLAG_SMART_SUSPEND on Cherry Trail devices 2020-12-17 14:18:49 +01:00
pwm-lpss.c pwm: lpss: Don't modify HW state in .remove callback 2021-04-09 15:21:18 +02:00
pwm-lpss.h pwm: lpss: Remove suspend/resume handlers 2020-09-06 15:38:01 +02:00
pwm-mediatek.c pwm: mediatek: Remove unused function 2021-04-23 18:47:45 +02:00
pwm-meson.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-mtk-disp.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-mxs.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-omap-dmtimer.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-pca9685.c pwm: pca9685: Improve runtime PM behavior 2021-04-23 18:45:49 +02:00
pwm-pxa.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-rcar.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-renesas-tpu.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-rockchip.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-samsung.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-sifive.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-sl28cpld.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-spear.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-sprd.c pwm: sprd: Refuse requests with unsupported polarity 2021-03-22 12:07:26 +01:00
pwm-sti.c pwm: sti: Free resources only after pwmchip_remove() 2021-04-09 14:46:58 +02:00
pwm-stm32-lp.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-stm32.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-stmpe.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-sun4i.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-tegra.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-tiecap.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-tiehrpwm.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-twl-led.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-twl.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
pwm-visconti.c pwm: visconti: Add Toshiba Visconti SoC PWM support 2021-04-23 19:05:13 +02:00
pwm-vt8500.c pwm: Always allocate PWM chip base ID dynamically 2021-03-22 11:53:00 +01:00
sysfs.c pwm: Allow store 64-bit duty cycle from sysfs interface 2020-09-24 09:18:14 +02:00