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SubjectRe: [PATCH v8 09/22] counter: Return error code on invalid modes
On Fri, 12 Feb 2021 21:13:33 +0900
William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> Only a select set of modes (function, action, etc.) are valid for a
> given device configuration. This patch ensures that invalid modes result
> in a return -EINVAL. Such a situation should never occur in reality, but
> it's good to define a default switch cases for the sake of making the
> intent of the code clear.

In many of these cases it may make sense to also return early
in the good paths rather than share a return 0 at the
end of the function?


>
> Cc: Syed Nayyar Waris <syednwaris@gmail.com>
> Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
> Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Alexandre Torgue <alexandre.torgue@st.com>
> Cc: David Lechner <david@lechnology.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
> drivers/counter/104-quad-8.c | 10 ++++++++++
> drivers/counter/microchip-tcb-capture.c | 6 ++++++
> drivers/counter/stm32-lptimer-cnt.c | 10 ++++++----
> drivers/counter/stm32-timer-cnt.c | 3 +++
> drivers/counter/ti-eqep.c | 3 +++
> 5 files changed, 28 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index 9a96296b0625..674263b4d2c4 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -273,6 +273,10 @@ static int quad8_function_set(struct counter_device *counter,
> *scale = 2;
> mode_cfg |= QUAD8_CMR_QUADRATURE_X4;
> break;
> + default:
> + /* should never reach this path */
> + mutex_unlock(&priv->lock);
> + return -EINVAL;
> }
> }
>
> @@ -367,6 +371,9 @@ static int quad8_action_get(struct counter_device *counter,
> case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
> *action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
> break;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
>
> return 0;
> @@ -529,6 +536,9 @@ static int quad8_count_mode_set(struct counter_device *counter,
> case COUNTER_COUNT_MODE_MODULO_N:
> cnt_mode = 3;
> break;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
>
> mutex_lock(&priv->lock);
> diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c
> index 710acc0a3704..ee979b011012 100644
> --- a/drivers/counter/microchip-tcb-capture.c
> +++ b/drivers/counter/microchip-tcb-capture.c
> @@ -133,6 +133,9 @@ static int mchp_tc_count_function_set(struct counter_device *counter,
> bmr |= ATMEL_TC_QDEN | ATMEL_TC_POSEN;
> cmr |= ATMEL_TC_ETRGEDG_RISING | ATMEL_TC_ABETRG | ATMEL_TC_XC0;
> break;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
>
> regmap_write(priv->regmap, ATMEL_TC_BMR, bmr);
> @@ -226,6 +229,9 @@ static int mchp_tc_count_action_set(struct counter_device *counter,
> case MCHP_TC_SYNAPSE_ACTION_BOTH_EDGE:
> edge = ATMEL_TC_ETRGEDG_BOTH;
> break;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
>
> return regmap_write_bits(priv->regmap,
> diff --git a/drivers/counter/stm32-lptimer-cnt.c b/drivers/counter/stm32-lptimer-cnt.c
> index 937439635d53..daf988e7b208 100644
> --- a/drivers/counter/stm32-lptimer-cnt.c
> +++ b/drivers/counter/stm32-lptimer-cnt.c
> @@ -206,9 +206,10 @@ static int stm32_lptim_cnt_function_set(struct counter_device *counter,
> priv->quadrature_mode = 1;
> priv->polarity = STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES;
> return 0;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
> -
> - return -EINVAL;
> }
>
> static ssize_t stm32_lptim_cnt_enable_read(struct counter_device *counter,
> @@ -326,9 +327,10 @@ static int stm32_lptim_cnt_action_get(struct counter_device *counter,
> case STM32_LPTIM_ENCODER_BOTH_EDGE:
> *action = priv->polarity;
> return 0;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
> -
> - return -EINVAL;
> }
>
> static int stm32_lptim_cnt_action_set(struct counter_device *counter,
> diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
> index ef2a974a2f10..431a3d08ed6c 100644
> --- a/drivers/counter/stm32-timer-cnt.c
> +++ b/drivers/counter/stm32-timer-cnt.c
> @@ -296,6 +296,9 @@ static int stm32_action_get(struct counter_device *counter,
> /* counts up/down on both TI1FP1 and TI2FP2 edges */
> *action = STM32_SYNAPSE_ACTION_BOTH_EDGES;
> break;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
>
> return 0;
> diff --git a/drivers/counter/ti-eqep.c b/drivers/counter/ti-eqep.c
> index a60aee1a1a29..7844fdf78a97 100644
> --- a/drivers/counter/ti-eqep.c
> +++ b/drivers/counter/ti-eqep.c
> @@ -192,6 +192,9 @@ static int ti_eqep_action_get(struct counter_device *counter,
> break;
> }
> break;
> + default:
> + /* should never reach this path */
> + return -EINVAL;
> }
>
> return 0;


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