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authorLinus Torvalds <torvalds@linux-foundation.org>2022-06-01 10:49:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-06-01 10:49:11 -0700
commit8eca6b0a647aabea3d1d2907dd6245fc436f98e7 (patch)
tree2741247faff78d81fca6d7337a679c210a7e5a89 /Documentation/driver-api
parentMerge tag 'rpmsg-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux (diff)
parentpwm: pwm-cros-ec: Add channel type support (diff)
downloadlinux-dev-8eca6b0a647aabea3d1d2907dd6245fc436f98e7.tar.xz
linux-dev-8eca6b0a647aabea3d1d2907dd6245fc436f98e7.zip
Merge tag 'pwm/for-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm
Pull pwm updates from Thierry Reding: "Quite a large number of conversions this time around, courtesy of Uwe who has been working tirelessly on these. No drivers of the legacy API are left at this point, so as a next step the old API can be removed. Support is added for a few new devices such as the Xilinx AXI timer- based PWMs and the PWM IP found on Sunplus SoCs. Other than that, there's a number of fixes, cleanups and optimizations" * tag 'pwm/for-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (43 commits) pwm: pwm-cros-ec: Add channel type support dt-bindings: google,cros-ec-pwm: Add the new -type compatible dt-bindings: Add mfd/cros_ec definitions pwm: Document that the pinstate of a disabled PWM isn't reliable pwm: twl-led: Implement .apply() callback pwm: lpc18xx: Implement .apply() callback pwm: mediatek: Implement .apply() callback pwm: lpc32xx: Implement .apply() callback pwm: tegra: Implement .apply() callback pwm: stmpe: Implement .apply() callback pwm: sti: Implement .apply() callback pwm: pwm-mediatek: Add support for MediaTek Helio X10 MT6795 dt-bindings: pwm: pwm-mediatek: Add documentation for MT6795 SoC pwm: tegra: Optimize period calculation pwm: renesas-tpu: Improve precision of period and duty_cycle calculation pwm: renesas-tpu: Improve maths to compute register settings pwm: renesas-tpu: Rename variables to match the usual naming pwm: renesas-tpu: Implement .apply() callback pwm: renesas-tpu: Make use of devm functions pwm: renesas-tpu: Make use of dev_err_probe() ...
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/pwm.rst6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst
index ccb06e485756..fd26c3d895b6 100644
--- a/Documentation/driver-api/pwm.rst
+++ b/Documentation/driver-api/pwm.rst
@@ -49,6 +49,12 @@ After being requested, a PWM has to be configured using::
This API controls both the PWM period/duty_cycle config and the
enable/disable state.
+
+As a consumer, don't rely on the output's state for a disabled PWM. If it's
+easily possible, drivers are supposed to emit the inactive state, but some
+drivers cannot. If you rely on getting the inactive state, use .duty_cycle=0,
+.enabled=true.
+
There is also a usage_power setting: If set, the PWM driver is only required to
maintain the power output but has more freedom regarding signal form.
If supported by the driver, the signal can be optimized, for example to improve