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authorJakub Kicinski <kuba@kernel.org>2024-06-27 12:12:07 -0700
committerJakub Kicinski <kuba@kernel.org>2024-06-27 12:14:11 -0700
commit193b9b200224dab4eaec407eb2955303a521f5b6 (patch)
tree95366182cc2871667a60613a921f7bfae0b9e2c7 /drivers/pwm/pwm-stm32.c
parentcce346d441399209bd582f1aaf190a7784dd12f8 (diff)
parentffb7aa9fedad817b9fa0d868a3065c4eeb1f68c4 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR. No conflicts. Adjacent changes: e3f02f32a050 ("ionic: fix kernel panic due to multi-buffer handling") d9c04209990b ("ionic: Mark error paths in the data path as unlikely") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers/pwm/pwm-stm32.c')
-rw-r--r--drivers/pwm/pwm-stm32.c23
1 files changed, 16 insertions, 7 deletions
diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index a2f231d13a9f..8bae3fd2b330 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -321,22 +321,30 @@ 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;
-
+ (u64)NSEC_PER_SEC * ((u64)priv->max_arr + 1));
if (prescaler > MAX_TIM_PSC)
return -EINVAL;
prd = mul_u64_u64_div_u64(period_ns, clk_get_rate(priv->clk),
(u64)NSEC_PER_SEC * (prescaler + 1));
+ if (!prd)
+ return -EINVAL;
/*
* All channels share the same prescaler and counter so when two
@@ -673,7 +681,8 @@ static int stm32_pwm_probe(struct platform_device *pdev)
* .apply() won't overflow.
*/
if (clk_get_rate(priv->clk) > 1000000000)
- return dev_err_probe(dev, -EINVAL, "Failed to lock clock\n");
+ return dev_err_probe(dev, -EINVAL, "Clock freq too high (%lu)\n",
+ clk_get_rate(priv->clk));
chip->ops = &stm32pwm_ops;