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counter: stm32-timer-cnt: fix ceiling miss-alignment with reload register

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Ceiling value may be miss-aligned with what's actually configured into the
ARR register. This is seen after probe as currently the ARR value is zero,
whereas ceiling value is set to the maximum. So:
- reading ceiling reports zero
- in case the counter gets enabled without any prior configuration,
  it won't count.
- in case the function gets set by the user 1st, (priv->ceiling) is used.

Fix it by getting rid of the cached "priv->ceiling" variable. Rather use
the ARR register value directly by using regmap read or write when needed.
There should be no drawback on performance as priv->ceiling isn't used in
performance critical path.
There's also no point in writing ARR while setting function (sms), so
it can be safely removed.

Fixes: ad29937e20 ("counter: Add STM32 Timer quadrature encoder")
Suggested-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1614793789-10346-1-git-send-email-fabrice.gasnier@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Fabrice Gasnier 2021-03-03 18:49:49 +01:00 committed by Jonathan Cameron
parent e4c3e13329
commit b14d72ac73
1 changed files with 3 additions and 8 deletions
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11
drivers/counter/stm32-timer-cnt.c
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@ -31,7 +31,6 @@ struct stm32_timer_cnt {
struct counter_device counter;
struct regmap *regmap;
struct clk *clk;
u32 ceiling;
u32 max_arr;
bool enabled;
struct stm32_timer_regs bak;
@ -75,8 +74,10 @@ static int stm32_count_write(struct counter_device *counter,
const unsigned long val)
{
struct stm32_timer_cnt *const priv = counter->priv;
u32 ceiling;
if (val > priv->ceiling)
regmap_read(priv->regmap, TIM_ARR, &ceiling);
if (val > ceiling)
return -EINVAL;
return regmap_write(priv->regmap, TIM_CNT, val);
@ -138,10 +139,6 @@ static int stm32_count_function_set(struct counter_device *counter,
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
/* TIMx_ARR register shouldn't be buffered (ARPE=0) */
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0);
regmap_write(priv->regmap, TIM_ARR, priv->ceiling);
regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, sms);
/* Make sure that registers are updated */
@ -199,7 +196,6 @@ static ssize_t stm32_count_ceiling_write(struct counter_device *counter,
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0);
regmap_write(priv->regmap, TIM_ARR, ceiling);
priv->ceiling = ceiling;
return len;
}
@ -374,7 +370,6 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
priv->regmap = ddata->regmap;
priv->clk = ddata->clk;
priv->ceiling = ddata->max_arr;
priv->max_arr = ddata->max_arr;
priv->counter.name = dev_name(dev);