kernel/linux.git/drivers/pwm, branch v6.1.124

pwm: imx27: Workaround of the pwm output bug when decrease the duty cycle

2024-12-14T18:53:22+00:00

[ Upstream commit a25351e4c7740eb22561a3ee4ef17611c6f410b0 ] Implement workaround for ERR051198 (https://www.nxp.com/docs/en/errata/IMX8MN_0N14Y.pdf) PWM output may not function correctly if the FIFO is empty when a new SAR value is programmed. Description: When the PWM FIFO is empty, a new value programmed to the PWM Sample register (PWM_PWMSAR) will be directly applied even if the current timer period has not expired. If the new SAMPLE value programmed in the PWM_PWMSAR register is less than the previous value, and the PWM counter register (PWM_PWMCNR) that contains the current COUNT value is greater than the new programmed SAMPLE value, the current period will not flip the level. This may result in an output pulse with a duty cycle of 100%. Workaround: Program the current SAMPLE value in the PWM_PWMSAR register before updating the new duty cycle to the SAMPLE value in the PWM_PWMSAR register. This will ensure that the new SAMPLE value is modified during a non-empty FIFO, and can be successfully updated after the period expires. Write the old SAR value before updating the new duty cycle to SAR. This avoids writing the new value into an empty FIFO. This only resolves the issue when the PWM period is longer than 2us (or <500kHz) because write register is not quick enough when PWM period is very short. Reproduce steps: cd /sys/class/pwm/pwmchip1/pwm0 echo 2000000000 > period # It is easy to observe by using long period echo 1000000000 > duty_cycle echo 1 > enable echo 8000 > duty_cycle # One full high pulse will be seen by scope Fixes: 166091b1894d ("[ARM] MXC: add pwm driver for i.MX SoCs") Reviewed-by: Jun Li Signed-off-by: Clark Wang Signed-off-by: Frank Li Link: https://lore.kernel.org/r/20241008194123.1943141-1-Frank.Li@nxp.com Signed-off-by: Uwe Kleine-König Signed-off-by: Sasha Levin

pwm: imx-tpm: Use correct MODULO value for EPWM mode

2024-11-14T12:15:14+00:00

commit cc6a931d1f3b412263d515fd93b21fc0ca5147fe upstream. The modulo register defines the period of the edge-aligned PWM mode (which is the only mode implemented). The reference manual states: "The EPWM period is determined by (MOD + 0001h) ..." So the value that is written to the MOD register must therefore be one less than the calculated period length. Return -EINVAL if the calculated length is already zero. A correct MODULO value is particularly relevant if the PWM has to output a high frequency due to a low period value. Fixes: 738a1cfec2ed ("pwm: Add i.MX TPM PWM driver support") Cc: stable@vger.kernel.org Signed-off-by: Erik Schumacher Link: https://lore.kernel.org/r/1a3890966d68b9f800d457cbf095746627495e18.camel@iris-sensing.com Signed-off-by: Uwe Kleine-König Signed-off-by: Greg Kroah-Hartman

pwm: atmel-tcb: Fix race condition and convert to guards

2024-08-03T06:48:55+00:00

[ Upstream commit 37f7707077f5ea2515bf4b1dc7fad43f8e12993e ] The hardware only supports a single period length for both PWM outputs. So atmel_tcb_pwm_config() checks the configuration of the other output if it's compatible with the currently requested setting. The register values are then actually updated in atmel_tcb_pwm_enable(). To make this race free the lock must be held during the whole process, so grab the lock in .apply() instead of individually in atmel_tcb_pwm_disable() and atmel_tcb_pwm_enable() which then also covers atmel_tcb_pwm_config(). To simplify handling, use the guard helper to let the compiler care for unlocking. Otherwise unlocking would be more difficult as there is more than one exit path in atmel_tcb_pwm_apply(). Fixes: 9421bade0765 ("pwm: atmel: add Timer Counter Block PWM driver") Signed-off-by: Uwe Kleine-König Acked-by: Nicolas Ferre Link: https://lore.kernel.org/r/20240709101806.52394-3-u.kleine-koenig@baylibre.com Signed-off-by: Uwe Kleine-König Signed-off-by: Sasha Levin

pwm: atmel-tcb: Don't track polarity in driver data

2024-08-03T06:48:55+00:00

[ Upstream commit 28a1dadc49e2902d0a7a2e8c699a15f93b1b6f40 ] struct atmel_tcb_pwm_device::polarity is only used in atmel_tcb_pwm_enable and atmel_tcb_pwm_disable(). These functions are only called by atmel_tcb_pwm_apply() after the member variable was assigned to state->polarity. So the value assigned in atmel_tcb_pwm_request() is never used and the member can be dropped from struct atmel_tcb_pwm_device. Signed-off-by: Uwe Kleine-König Reviewed-by: Claudiu Beznea Signed-off-by: Thierry Reding Stable-dep-of: 37f7707077f5 ("pwm: atmel-tcb: Fix race condition and convert to guards") Signed-off-by: Sasha Levin

pwm: atmel-tcb: Unroll atmel_tcb_pwm_set_polarity() into only caller

2024-08-03T06:48:55+00:00

[ Upstream commit 9a6ac822a2153d583b0da95b8693e954b5f4203a ] atmel_tcb_pwm_set_polarity() is only called once and effectively wraps an assignment only. Replace the function call by the respective assignment. Signed-off-by: Uwe Kleine-König Reviewed-by: Claudiu Beznea Signed-off-by: Thierry Reding Stable-dep-of: 37f7707077f5 ("pwm: atmel-tcb: Fix race condition and convert to guards") Signed-off-by: Sasha Levin

pwm: atmel-tcb: Put per-channel data into driver data

2024-08-03T06:48:55+00:00

[ Upstream commit 78dca23bd6706dd6a3cdb5c0052f48794b4d2bed ] This simplifies the code, reduces the number of memory allocations and pointer dereferences. Signed-off-by: Uwe Kleine-König Reviewed-by: Claudiu Beznea Signed-off-by: Thierry Reding Stable-dep-of: 37f7707077f5 ("pwm: atmel-tcb: Fix race condition and convert to guards") Signed-off-by: Sasha Levin

pwm: stm32: Always do lazy disabling

2024-08-03T06:48:55+00:00

[ Upstream commit 7346e7a058a2c9aa9ff1cc699c7bf18a402d9f84 ] When the state changes from enabled to disabled, polarity, duty_cycle and period are not configured in hardware and TIM_CCER_CCxE is just cleared. However if the state changes from one disabled state to another, all parameters are written to hardware because the early exit from stm32_pwm_apply() is only taken if the pwm is currently enabled. This yields surprises like: Applying { .period = 1, .duty_cycle = 0, .enabled = false } succeeds if the pwm is initially on, but fails if it's already off because 1 is a too small period. Update the check for lazy disable to always exit early if the target state is disabled, no matter what is currently configured. Fixes: 7edf7369205b ("pwm: Add driver for STM32 plaftorm") Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20240703110010.672654-2-u.kleine-koenig@baylibre.com Signed-off-by: Uwe Kleine-König Signed-off-by: Sasha Levin

pwm: stm32: Refuse too small period requests

2024-07-05T07:31:59+00:00

commit c45fcf46ca2368dafe7e5c513a711a6f0f974308 upstream. If period_ns is small, prd might well become 0. Catch that case because otherwise with regmap_write(priv->regmap, TIM_ARR, prd - 1); a few lines down quite a big period is configured. Fixes: 7edf7369205b ("pwm: Add driver for STM32 plaftorm") Cc: stable@vger.kernel.org Reviewed-by: Trevor Gamblin Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/b86f62f099983646f97eeb6bfc0117bb2d0c340d.1718979150.git.u.kleine-koenig@baylibre.com Signed-off-by: Uwe Kleine-König Signed-off-by: Greg Kroah-Hartman

pwm: sti: Simplify probe function using devm functions

2024-06-12T09:03:14+00:00

[ Upstream commit 5bb0b194aeee5d5da6881232f4e9989b35957c25 ] Instead of of_clk_get_by_name() use devm_clk_get_prepared() which has several advantages: - Combines getting the clock and a call to clk_prepare(). The latter can be dropped from sti_pwm_probe() accordingly. - Cares for calling clk_put() which is missing in both probe's error path and the remove function. - Cares for calling clk_unprepare() which can be dropped from the error paths and the remove function. (Note that not all error path got this right.) With additionally using devm_pwmchip_add() instead of pwmchip_add() the remove callback can be dropped completely. With it the last user of platform_get_drvdata() goes away and so platform_set_drvdata() can be dropped from the probe function, too. Fixes: 378fe115d19d ("pwm: sti: Add new driver for ST's PWM IP") Link: https://lore.kernel.org/r/81f0e1d173652f435afda6719adaed1922fe059a.1710068192.git.u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König Signed-off-by: Sasha Levin

pwm: sti: Prepare removing pwm_chip from driver data

2024-06-12T09:03:14+00:00

[ Upstream commit 54272761ce7c475fa30a31b59b0cb89f7652b39e ] This prepares the driver for further changes that will drop struct pwm_chip chip from struct sti_pwm_chip. Use the pwm_chip as driver data instead of the sti_pwm_chip to get access to the pwm_chip in sti_pwm_remove() without using pc->chip. Link: https://lore.kernel.org/r/56d53372aacff6871df4d6c6779c9dac94592696.1707900770.git.u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König Stable-dep-of: 5bb0b194aeee ("pwm: sti: Simplify probe function using devm functions") Signed-off-by: Sasha Levin