From ae14643f35f2d8e9881b7f5462f4e2c381d09e5f Mon Sep 17 00:00:00 2001 From: Erik Schumacher Date: Fri, 25 Oct 2024 08:37:00 +0000 Subject: [PATCH] pwm: imx-tpm: Use correct MODULO value for EPWM mode MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- drivers/pwm/pwm-imx-tpm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c index 871527b78..6e8db0acf 100755 --- a/drivers/pwm/pwm-imx-tpm.c +++ b/drivers/pwm/pwm-imx-tpm.c @@ -106,7 +106,9 @@ static int pwm_imx_tpm_round_state(struct pwm_chip *chip, p->prescale = prescale; period_count = (clock_unit + ((1 << prescale) >> 1)) >> prescale; - p->mod = period_count; + if (period_count == 0) + return -EINVAL; + p->mod = period_count - 1; /* calculate real period HW can support */ tmp = (u64)period_count << prescale;