WSL2-Linux-Kernel/drivers/pwm
Sven Van Asbroeck 9cc5f232a4 pwm: pca9685: Fix PWM/GPIO inter-operation
This driver allows pwms to be requested as gpios via gpiolib. Obviously,
it should not be allowed to request a GPIO when its corresponding PWM is
already requested (and vice versa). So it requires some exclusion code.

Given that the PWMm and GPIO cores are not synchronized with respect to
each other, this exclusion code will also require proper
synchronization.

Such a mechanism was in place, but was inadvertently removed by Uwe's
clean-up in commit e926b12c61 ("pwm: Clear chip_data in pwm_put()").

Upon revisiting the synchronization mechanism, we found that
theoretically, it could allow two threads to successfully request
conflicting PWMs/GPIOs.

Replace with a bitmap which tracks PWMs in-use, plus a mutex. As long as
PWM and GPIO's respective request/free functions modify the in-use
bitmap while holding the mutex, proper synchronization will be
guaranteed.

Reported-by: YueHaibing <yuehaibing@huawei.com>
Fixes: e926b12c61 ("pwm: Clear chip_data in pwm_put()")
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: YueHaibing <yuehaibing@huawei.com>
Link: https://lkml.org/lkml/2019/5/31/963
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[cg: Tested on an i.MX6Q board with two NXP PCA9685 chips]
Tested-by: Clemens Gruber <clemens.gruber@pqgruber.com>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com> # cg's rebase
Link: https://lore.kernel.org/lkml/20200330160238.GD2817345@ulmo/
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2020-04-03 21:41:42 +02:00
..
Kconfig pwm: jz4740: Obtain regmap from parent node 2020-03-30 18:03:09 +02:00
Makefile bus/ti-pwmss: move TI PWMSS driver from PWM to bus subsystem 2019-10-17 21:17:42 +01:00
core.c pwm: Make pwm_apply_state_debug() static 2020-04-03 21:41:09 +02:00
pwm-ab8500.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
pwm-atmel-hlcdc.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-atmel-tcb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
pwm-atmel.c pwm: atmel: Implement .get_state() 2020-01-08 13:47:46 +01:00
pwm-bcm-iproc.c pwm: bcm-iproc: Prevent unloading the driver module while in use 2019-11-08 18:38:06 +01:00
pwm-bcm-kona.c
pwm-bcm2835.c pwm: bcm2835: Dynamically allocate base 2020-03-30 16:55:25 +02:00
pwm-berlin.c
pwm-brcmstb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
pwm-clps711x.c
pwm-crc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
pwm-cros-ec.c pwm: cros-ec: Cache duty cycle value 2019-12-09 10:05:42 +01:00
pwm-ep93xx.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
pwm-fsl-ftm.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-hibvt.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-img.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 178 2019-05-30 11:29:19 -07:00
pwm-imx-tpm.c pwm: imx-tpm: Remove unused includes 2020-03-30 16:55:26 +02:00
pwm-imx1.c
pwm-imx27.c pwm: imx27: Remove unused include of of_device.h 2020-03-30 16:55:26 +02:00
pwm-jz4740.c pwm: jz4740: Allow selection of PWM channels 0 and 1 2020-03-30 18:03:10 +02:00
pwm-lp3943.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 372 2019-06-05 17:37:10 +02:00
pwm-lpc18xx-sct.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 178 2019-05-30 11:29:19 -07:00
pwm-lpc32xx.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 372 2019-06-05 17:37:10 +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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
pwm-lpss.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-lpss.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
pwm-mediatek.c pwm: mediatek: Add MT7629 compatible string 2019-09-26 13:27:50 +02:00
pwm-meson.c pwm: meson: Remove redundant assignment to variable fin_freq 2020-04-03 21:40:56 +02:00
pwm-mtk-disp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
pwm-mxs.c pwm: mxs: Remove unused include of of_address.h 2020-03-30 16:55:27 +02:00
pwm-omap-dmtimer.c pwm: omap-dmtimer: Implement .apply callback 2020-03-30 18:03:08 +02:00
pwm-pca9685.c pwm: pca9685: Fix PWM/GPIO inter-operation 2020-04-03 21:41:42 +02:00
pwm-puv3.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
pwm-pxa.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
pwm-rcar.c pwm: rcar: Fix late Runtime PM enablement 2020-03-30 18:03:05 +02:00
pwm-renesas-tpu.c pwm: renesas-tpu: Drop confusing registered message 2020-03-30 18:03:06 +02:00
pwm-rockchip.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-samsung.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 178 2019-05-30 11:29:19 -07:00
pwm-sifive.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-spear.c
pwm-sprd.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
pwm-sti.c pwm: Remove dev_err() usage after platform_get_irq() 2019-09-21 00:58:35 +02:00
pwm-stm32-lp.c pwm: stm32-lp: Add check in case requested period cannot be achieved 2019-09-21 03:25:10 +02:00
pwm-stm32.c pwm: stm32: Remove automatic output enable 2020-01-20 13:47:36 +01:00
pwm-stmpe.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
pwm-sun4i.c pwm: sun4i: Remove redundant needs_delay 2020-03-30 18:03:08 +02:00
pwm-tegra.c pwm: tegra: Add support for Tegra194 2020-03-30 18:03:04 +02:00
pwm-tiecap.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
pwm-tiehrpwm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
pwm-twl-led.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234 2019-06-19 17:09:07 +02:00
pwm-twl.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234 2019-06-19 17:09:07 +02:00
pwm-vt8500.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
pwm-zx.c pwm: Ensure pwm_apply_state() doesn't modify the state argument 2019-09-21 03:25:10 +02:00
sysfs.c pwm: Changes for v5.3-rc1 2019-07-09 08:57:45 -07:00