[PATCH 5.10 136/157] counter: stm32-timer-cnt: fix ceiling miss-alignment with reload register
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-03-22 12:53:14
Also in:
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From: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
commit b14d72ac731753708a7c1a6b3657b9312b6f0042 upstream.
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: ad29937e206f ("counter: Add STM32 Timer quadrature encoder")
Suggested-by: William Breathitt Gray <redacted>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Acked-by: William Breathitt Gray <redacted>
Cc: <redacted>
Link: https://lore.kernel.org/r/1614793789-10346-1-git-send-email-fabrice.gasnier@foss.st.com (local)
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/counter/stm32-timer-cnt.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
--- a/drivers/counter/stm32-timer-cnt.c
+++ b/drivers/counter/stm32-timer-cnt.c@@ -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 coun 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(stru 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 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 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);