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While driving a PWM via the sysfs API it's hard to determine the right order of writes to the pseudo files "period" and "duty_cycle": If you want to go from duty_cycle/period = 50/100 to 150/300 you have to write period first (because 150/100 is invalid). If however you start at 400/500 the duty_cycle must be configured first. The rule that works is: If you increase period write period first, otherwise write duty_cycle first. A complication however is that it's usually sensible to configure the polarity before both period and duty_cycle. This can only be done if the current state's duty_cycle and period configuration isn't bogus though. It is still worse (but I think only theoretic) if you have a PWM that only supports inverted polarity and you start with period = 0 and polarity = normal. Then you can change neither period (because polarity = normal is refused) nor polarity (because there is still period = 0). To simplify the corner cases for userspace, let invalid target states pass if the current state is invalid already. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Link: https://lore.kernel.org/r/20240628103519.105020-2-u.kleine-koenig@baylibre.com Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org> |
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| .. | ||
| core.c | ||
| Kconfig | ||
| Makefile | ||
| pwm-ab8500.c | ||
| pwm-apple.c | ||
| pwm-atmel-hlcdc.c | ||
| pwm-atmel-tcb.c | ||
| pwm-atmel.c | ||
| pwm-axi-pwmgen.c | ||
| pwm-bcm2835.c | ||
| pwm-bcm-iproc.c | ||
| pwm-bcm-kona.c | ||
| pwm-berlin.c | ||
| pwm-brcmstb.c | ||
| pwm-clk.c | ||
| pwm-clps711x.c | ||
| pwm-crc.c | ||
| pwm-cros-ec.c | ||
| pwm-dwc-core.c | ||
| pwm-dwc.c | ||
| pwm-dwc.h | ||
| pwm-ep93xx.c | ||
| pwm-fsl-ftm.c | ||
| pwm-gpio.c | ||
| pwm-hibvt.c | ||
| pwm-img.c | ||
| pwm-imx1.c | ||
| pwm-imx27.c | ||
| pwm-imx-tpm.c | ||
| pwm-intel-lgm.c | ||
| pwm-iqs620a.c | ||
| pwm-jz4740.c | ||
| pwm-keembay.c | ||
| pwm-lp3943.c | ||
| pwm-lpc18xx-sct.c | ||
| pwm-lpc32xx.c | ||
| pwm-lpss-pci.c | ||
| pwm-lpss-platform.c | ||
| pwm-lpss.c | ||
| pwm-lpss.h | ||
| pwm-mediatek.c | ||
| pwm-meson.c | ||
| pwm-microchip-core.c | ||
| pwm-mtk-disp.c | ||
| pwm-mxs.c | ||
| pwm-ntxec.c | ||
| pwm-omap-dmtimer.c | ||
| pwm-pca9685.c | ||
| pwm-pxa.c | ||
| pwm-raspberrypi-poe.c | ||
| pwm-rcar.c | ||
| pwm-renesas-tpu.c | ||
| pwm-rockchip.c | ||
| pwm-rz-mtu3.c | ||
| pwm-samsung.c | ||
| pwm-sifive.c | ||
| pwm-sl28cpld.c | ||
| pwm-spear.c | ||
| pwm-sprd.c | ||
| pwm-sti.c | ||
| pwm-stm32-lp.c | ||
| pwm-stm32.c | ||
| pwm-stmpe.c | ||
| pwm-sun4i.c | ||
| pwm-sunplus.c | ||
| pwm-tegra.c | ||
| pwm-tiecap.c | ||
| pwm-tiehrpwm.c | ||
| pwm-twl-led.c | ||
| pwm-twl.c | ||
| pwm-visconti.c | ||
| pwm-vt8500.c | ||
| pwm-xilinx.c | ||