From b82352b46d8fd98824a967da8fbe52855b66cbff Mon Sep 17 00:00:00 2001 From: Fabrice Gasnier Date: Wed, 3 Mar 2021 18:49:49 +0100 Subject: [PATCH] counter: stm32-timer-cnt: fix ceiling miss-alignment with reload register BugLink: https://bugs.launchpad.net/bugs/1926489 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 Signed-off-by: Fabrice Gasnier Acked-by: William Breathitt Gray Cc: Link: https://lore.kernel.org/r/1614793789-10346-1-git-send-email-fabrice.gasnier@foss.st.com Signed-off-by: Jonathan Cameron [sudip: adjuct context] Signed-off-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Stefan Bader --- drivers/counter/stm32-timer-cnt.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c index 75e08a98d09b..889ea7a6ed63 100644 --- a/drivers/counter/stm32-timer-cnt.c +++ b/drivers/counter/stm32-timer-cnt.c @@ -24,7 +24,6 @@ struct stm32_timer_cnt { struct counter_device counter; struct regmap *regmap; struct clk *clk; - u32 ceiling; u32 max_arr; }; @@ -67,14 +66,15 @@ static int stm32_count_write(struct counter_device *counter, struct counter_count_write_value *val) { struct stm32_timer_cnt *const priv = counter->priv; - u32 cnt; + u32 cnt, ceiling; int err; err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val); if (err) return err; - if (cnt > priv->ceiling) + regmap_read(priv->regmap, TIM_ARR, &ceiling); + if (cnt > ceiling) return -EINVAL; return regmap_write(priv->regmap, TIM_CNT, cnt); @@ -136,10 +136,6 @@ 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 */ @@ -197,7 +193,6 @@ 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; } @@ -369,7 +364,6 @@ 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); -- 2.39.5