5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Erik Schumacher <erik.schumacher@xxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Erik Schumacher <erik.schumacher@xxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1a3890966d68b9f800d457cbf095746627495e18.camel@xxxxxxxxxxxxxxxx
Signed-off-by: Uwe Kleine-König <ukleinek@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -108,7 +108,9 @@ 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;
