diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index e68f8ec867b9..28e90ea1189e 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -1,5 +1,5 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
+	// SPDX-License-Identifier: GPL-2.0
+	/*
  * Copyright (C) STMicroelectronics 2016
  *
  * Author: Gerald Baeza <gerald.baeza@st.com>
@@ -321,19 +321,23 @@ static int stm32_pwm_config(struct stm32_pwm *priv, unsigned int ch,
 	 * First we need to find the minimal value for prescaler such that
 	 *
 	 *        period_ns * clkrate
-	 *   ------------------------------
+	 *   ------------------------------ < max_arr + 1
 	 *   NSEC_PER_SEC * (prescaler + 1)
 	 *
-	 * isn't bigger than max_arr.
+	 * This equation is equivalent to
+	 *
+	 *        period_ns * clkrate
+	 *   ---------------------------- < prescaler + 1
+	 *   NSEC_PER_SEC * (max_arr + 1)
+	 *
+	 * Using integer division and knowing that the right hand side is
+	 * integer, this is further equivalent to
+	 *
+	 *   (period_ns * clkrate) // (NSEC_PER_SEC * (max_arr + 1)) ≤ prescaler
 	 */
 
 	prescaler = mul_u64_u64_div_u64(period_ns, clk_get_rate(priv->clk),
-					(u64)NSEC_PER_SEC * priv->max_arr);
-	if (prescaler > 0)
-		prescaler -= 1;
-
-	if (prescaler > MAX_TIM_PSC)
-		return -EINVAL;
+					(u64)NSEC_PER_SEC * ((u64)priv->max_arr + 1));
 
 	prd = mul_u64_u64_div_u64(period_ns, clk_get_rate(priv->clk),
 				  (u64)NSEC_PER_SEC * (prescaler + 1));