Re: [PATCH v3 2/2] reset: make optional functions really optional

[Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>]

Hi Philipp

On 1/13/2017 9:11 AM, Philipp Zabel wrote:
> Hi Ramiro,
> 
> Am Donnerstag, den 12.01.2017, 18:34 +0000 schrieb Ramiro Oliveira:
>> "The *_get_optional_* functions weren't really optional so this patch
>> makes them really optional.
>>
>> These *_get_optional_* functions will now return NULL instead of an error
>> if no matching reset phandle is found in the DT, and all the
>> reset_control_* functions now accept NULL rstc pointers.
>>
>> Signed-off-by: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
>> ---
>>  drivers/reset/core.c  | 59 ++++++++++++++++++++++++++++++++++++++++-----------
>>  include/linux/reset.h | 45 ++++++++++++++++++++++-----------------
>>  2 files changed, 73 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
>> index 272c1e4ecb5c..7b679b0bfef8 100644
>> --- a/drivers/reset/core.c
>> +++ b/drivers/reset/core.c
>> @@ -143,12 +143,18 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register);
>>   * a no-op.
>>   * Consumers must not use reset_control_(de)assert on shared reset lines when
>>   * reset_control_reset has been used.
>> + *
>> + * If rstc is NULL it is an optional reset and the function will just
>> + * return 0.
>>   */
>>  int reset_control_reset(struct reset_control *rstc)
>>  {
>>  	int ret;
>>  
>> -	if (WARN_ON(IS_ERR_OR_NULL(rstc)))
>> +	if (!rstc)
>> +		return 0;
>> +
>> +	if (WARN_ON(IS_ERR(rstc)))
>>  		return -EINVAL;
>>  
>>  	if (!rstc->rcdev->ops->reset)
>> @@ -182,10 +188,17 @@ EXPORT_SYMBOL_GPL(reset_control_reset);
>>   * internal state to be reset, but must be prepared for this to happen.
>>   * Consumers must not use reset_control_reset on shared reset lines when
>>   * reset_control_(de)assert has been used.
>> + * return 0.
>> + *
>> + * If rstc is NULL it is an optional reset and the function will just
>> + * return 0.
>>   */
>>  int reset_control_assert(struct reset_control *rstc)
>>  {
>> -	if (WARN_ON(IS_ERR_OR_NULL(rstc)))
>> +	if (!rstc)
>> +		return 0;
>> +
>> +	if (WARN_ON(IS_ERR(rstc)))
>>  		return -EINVAL;
>>  
>>  	if (!rstc->rcdev->ops->assert)
>> @@ -213,10 +226,17 @@ EXPORT_SYMBOL_GPL(reset_control_assert);
>>   * After calling this function, the reset is guaranteed to be deasserted.
>>   * Consumers must not use reset_control_reset on shared reset lines when
>>   * reset_control_(de)assert has been used.
>> + * return 0.
>> + *
>> + * If rstc is NULL it is an optional reset and the function will just
>> + * return 0.
>>   */
>>  int reset_control_deassert(struct reset_control *rstc)
>>  {
>> -	if (WARN_ON(IS_ERR_OR_NULL(rstc)))
>> +	if (!rstc)
>> +		return 0;
>> +
>> +	if (WARN_ON(IS_ERR(rstc)))
>>  		return -EINVAL;
>>  
>>  	if (!rstc->rcdev->ops->deassert)
>> @@ -237,12 +257,15 @@ EXPORT_SYMBOL_GPL(reset_control_deassert);
>>  /**
>>   * reset_control_status - returns a negative errno if not supported, a
>>   * positive value if the reset line is asserted, or zero if the reset
>> - * line is not asserted.
>> + * line is not asserted or if the desc is NULL (optional reset).
>>   * @rstc: reset controller
>>   */
>>  int reset_control_status(struct reset_control *rstc)
>>  {
>> -	if (WARN_ON(IS_ERR_OR_NULL(rstc)))
>> +	if (!rstc)
>> +		return 0;
>> +
>> +	if (WARN_ON(IS_ERR(rstc)))
>>  		return -EINVAL;
>>  
>>  	if (rstc->rcdev->ops->status)
>> @@ -299,7 +322,8 @@ static void __reset_control_put(struct reset_control *rstc)
>>  }
>>  
>>  struct reset_control *__of_reset_control_get(struct device_node *node,
>> -				     const char *id, int index, bool shared)
>> +				     const char *id, int index, bool shared,
>> +				     bool optional)
>>  {
>>  	struct reset_control *rstc;
>>  	struct reset_controller_dev *r, *rcdev;
>> @@ -313,14 +337,24 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
>>  	if (id) {
>>  		index = of_property_match_string(node,
>>  						 "reset-names", id);
>> -		if (index < 0)
>> -			return ERR_PTR(-ENOENT);
>> +		if (index < 0) {
>> +			if (optional)
>> +				return NULL;
>> +			else
>> +				return (index == -EILSEQ) ?
>> +					ERR_PTR(index) : ERR_PTR(-ENOENT);
> 
> That is not what I meant. I think reset_control_get should return an
> error on EILSEQ even if optional is true, since that means there are
> resets specified in the DT, but the reset-names property is broken.
> How about:
> 		if (index == -EILSEQ)
> 			return ERR_PTR(index);
> 		if (index < 0)
> 			return optional ? NULL : ERR_PTR(-ENOENT);
> 

When you first suggested I wasn't entirely sure what you meant, but now it makes
total sense to me.

I should have asked you about it before implementing it.

>> +		}
>>  	}
>>  
>>  	ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
>>  					 index, &args);
>> -	if (ret)
>> -		return ERR_PTR(ret);
>> +	if (ret) {
>> +		if (optional)
>> +			return NULL;
>> +		else
>> +			return (index == -EINVAL) ?
>> +				ERR_PTR(index) : ERR_PTR(-ENOENT);
>> +	}
> 
> That is not what I meant either. If the phandle parsing fails with
> of_phandle_iterator_next returning -EINVAL, that should be passed along
> in the optional case: that happens when we've already found a matching
> entry in reset-names, but the resets property is broken.
> How about:
> 	if (ret == -EINVAL)
> 		return ERR_PTR(ret);
> 	if (ret)
> 		return optional ? NULL : ERR_PTR(ret);
> 

Same as above.

> regards
> Philipp
> 

I'll refactor the code and send a new patch ASAP.

BRs,
Ramiro