On 11/22/22 08:33, William Breathitt Gray wrote:
> On Tue, Nov 22, 2022 at 02:27:50AM -0500, William Breathitt Gray wrote:
>> On Wed, Nov 23, 2022 at 02:36:09PM +0100, Fabrice Gasnier wrote:
>>> The ARR (auto reload register) and CMP (compare) registers are
>>> successively written. The status bits to check the update of these
>>> registers are polled together with regmap_read_poll_timeout().
>>> The condition to end the loop may become true, even if one of the register
>>> isn't correctly updated.
>>> So ensure both status bits are set before clearing them.
>>>
>>> Fixes: d8958824cf07 ("iio: counter: Add support for STM32 LPTimer")
>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx>
>>> ---
>>> drivers/counter/stm32-lptimer-cnt.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/counter/stm32-lptimer-cnt.c b/drivers/counter/stm32-lptimer-cnt.c
>>> index d6b80b6dfc28..8439755559b2 100644
>>> --- a/drivers/counter/stm32-lptimer-cnt.c
>>> +++ b/drivers/counter/stm32-lptimer-cnt.c
>>> @@ -69,7 +69,7 @@ static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
>>>
>>> /* ensure CMP & ARR registers are properly written */
>>> ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val,
>>> - (val & STM32_LPTIM_CMPOK_ARROK),
>>> + (val & STM32_LPTIM_CMPOK_ARROK) == STM32_LPTIM_CMPOK_ARROK,
>>
>> This is a reasonable fix, but I don't like seeing so much happening in
>> an argument list -- it's easy to misunderstand what's going on which can
>> lead to further bugs the future. Pull out this condition to a dedicated
>> bool variable with a comment explaining why we need the equivalence
>> check (i.e. to ensure both status bits are set and not just one).
>>
>> William Breathitt Gray
>
> Alternatively, you could pull out just (val & STM32_LPTIM_CMPOK_ARROK)
> to a separate variable and keep the equivalence condition inline if you
> think it'll be clearer that way.
Hi William,
I'm not sure to fully understand your proposal here.
Could you clarify ?
regmap_read_poll_timeout() macro requires:
* @val: Unsigned integer variable to read the value into
* @cond: Break condition (usually involving @val)
So do you wish I introduce a macro that abstracts the condition check ?
(val & STM32_LPTIM_CMPOK_ARROK) == STM32_LPTIM_CMPOK_ARROK
Best regards,
Fabrice
>
> William Breathitt Gray
