5.15-stable review patch. If anyone has any objections, please let me know.
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From: Erik Schumacher erik.schumacher@iris-sensing.com
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 erik.schumacher@iris-sensing.com Link: https://lore.kernel.org/r/1a3890966d68b9f800d457cbf095746627495e18.camel@iri... Signed-off-by: Uwe Kleine-König ukleinek@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pwm/pwm-imx-tpm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- 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(struc 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;