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    SubjectRe: [PATCH v10 18/33] counter: Return error code on invalid modes
    On Fri, Mar 19, 2021 at 08:00:37PM +0900, William Breathitt Gray 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.
    >
    > 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 | 20 +++++++----

    For the 104-quad-8 driver:
    Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>

    > drivers/counter/microchip-tcb-capture.c | 6 ++++
    > drivers/counter/stm32-lptimer-cnt.c | 10 +++---
    > drivers/counter/ti-eqep.c | 45 +++++++++++--------------
    > 4 files changed, 46 insertions(+), 35 deletions(-)
    >
    > diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
    > index 09d779544969..b7d6c1c43655 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;
    > }
    > }
    >
    > @@ -349,7 +353,7 @@ static int quad8_action_get(struct counter_device *counter,
    > case QUAD8_COUNT_FUNCTION_PULSE_DIRECTION:
    > if (synapse->signal->id == signal_a_id)
    > *action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
    > - break;
    > + return 0;
    > case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
    > if (synapse->signal->id == signal_a_id) {
    > quad8_direction_get(counter, count, &direction);
    > @@ -359,17 +363,18 @@ static int quad8_action_get(struct counter_device *counter,
    > else
    > *action = QUAD8_SYNAPSE_ACTION_FALLING_EDGE;
    > }
    > - break;
    > + return 0;
    > case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
    > if (synapse->signal->id == signal_a_id)
    > *action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
    > - break;
    > + return 0;
    > case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
    > *action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
    > - break;
    > + return 0;
    > + default:
    > + /* should never reach this path */
    > + return -EINVAL;
    > }
    > -
    > - return 0;
    > }
    >
    > static const struct counter_ops quad8_ops = {
    > @@ -529,6 +534,9 @@ 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 51b8af80f98b..0c9a61962911 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 c19d998df5ba..78f383b77bd2 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/ti-eqep.c b/drivers/counter/ti-eqep.c
    > index 65df9ef5b5bc..878725c2f010 100644
    > --- a/drivers/counter/ti-eqep.c
    > +++ b/drivers/counter/ti-eqep.c
    > @@ -157,44 +157,39 @@ static int ti_eqep_action_get(struct counter_device *counter,
    > * QEPA and QEPB trigger QCLK.
    > */
    > *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES;
    > - break;
    > + return 0;
    > case TI_EQEP_COUNT_FUNC_DIR_COUNT:
    > /* In direction-count mode only rising edge of QEPA is counted
    > * and QEPB gives direction.
    > */
    > - switch (synapse->signal->id) {
    > - case TI_EQEP_SIGNAL_QEPA:
    > - *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
    > - break;
    > - default:
    > + if (synapse->signal->id == TI_EQEP_SIGNAL_QEPB)
    > *action = TI_EQEP_SYNAPSE_ACTION_NONE;
    > - break;
    > - }
    > - break;
    > + else
    > + *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
    > + return 0;
    > case TI_EQEP_COUNT_FUNC_UP_COUNT:
    > case TI_EQEP_COUNT_FUNC_DOWN_COUNT:
    > /* In up/down-count modes only QEPA is counted and QEPB is not
    > * used.
    > */
    > - switch (synapse->signal->id) {
    > - case TI_EQEP_SIGNAL_QEPA:
    > - err = regmap_read(priv->regmap16, QDECCTL, &qdecctl);
    > - if (err)
    > - return err;
    > -
    > - if (qdecctl & QDECCTL_XCR)
    > - *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES;
    > - else
    > - *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
    > - break;
    > - default:
    > + if (synapse->signal->id == TI_EQEP_SIGNAL_QEPB) {
    > *action = TI_EQEP_SYNAPSE_ACTION_NONE;
    > - break;
    > + return 0;
    > }
    > - break;
    > - }
    >
    > - return 0;
    > + err = regmap_read(priv->regmap16, QDECCTL, &qdecctl);
    > + if (err)
    > + return err;
    > +
    > + if (qdecctl & QDECCTL_XCR)
    > + *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES;
    > + else
    > + *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
    > + return 0;
    > + default:
    > + /* should never reach this path */
    > + return -EINVAL;
    > + }
    > }
    >
    > static const struct counter_ops ti_eqep_counter_ops = {
    > --
    > 2.30.2
    >

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