Re: [PATCH] counter: stm32-timer-cnt: Add check for clk_enable()

From: William Breathitt Gray
Date: Mon Nov 04 2024 - 09:25:18 EST


On Sun, Nov 03, 2024 at 06:25:02PM +0000, Jiasheng Jiang wrote:
> From: Jiasheng Jiang <jiashengjiangcool@xxxxxxxxxxx>
>
> Add check for the return value of clk_enable() in order to catch the
> potential exception.
>
> Fixes: c5b8425514da ("counter: stm32-timer-cnt: add power management support")
> Fixes: ad29937e206f ("counter: Add STM32 Timer quadrature encoder")
> Signed-off-by: Jiasheng Jiang <jiashengjiangcool@xxxxxxxxxxx>
> ---
> drivers/counter/stm32-timer-cnt.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
> index 186e73d6ccb4..0593c9b73992 100644
> --- a/drivers/counter/stm32-timer-cnt.c
> +++ b/drivers/counter/stm32-timer-cnt.c
> @@ -214,11 +214,15 @@ static int stm32_count_enable_write(struct counter_device *counter,
> {
> struct stm32_timer_cnt *const priv = counter_priv(counter);
> u32 cr1;
> + int ret;
>
> if (enable) {
> regmap_read(priv->regmap, TIM_CR1, &cr1);
> - if (!(cr1 & TIM_CR1_CEN))
> - clk_enable(priv->clk);
> + if (!(cr1 & TIM_CR1_CEN)) {
> + ret = clk_enable(priv->clk);
> + if (ret)
> + return ret;
> + }
>
> regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
> TIM_CR1_CEN);
> @@ -816,7 +820,9 @@ static int __maybe_unused stm32_timer_cnt_resume(struct device *dev)
> return ret;
>
> if (priv->enabled) {
> - clk_enable(priv->clk);
> + ret = clk_enable(priv->clk);
> + if (ret)
> + return ret;
>
> /* Restore registers that may have been lost */
> regmap_write(priv->regmap, TIM_SMCR, priv->bak.smcr);
> --
> 2.25.1

It's not necessarily clear that an error in the count_enable_write()
callback or cnt_resume() callback is due to a clk_enable() failure. You
should call dev_err before returning to indicate the reason for the
error code.

William Breathitt Gray

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