RE: [PATCH] usb: cdns3: platform_get_irq_byname_optional instead platform_get_irq_byname

[Pawel Laszczak]

Roger,

>Pawel,
>
>On 05/10/2020 08:54, Pawel Laszczak wrote:
>> Roger,
>>>
>>> Pawel,
>>>
>>> On 02/10/2020 12:08, Pawel Laszczak wrote:
>>>> Roger,
>>>>
>>>>>
>>>>> On 30/09/2020 09:57, Pawel Laszczak wrote:
>>>>>> To avoid duplicate error information patch replaces platform_get_irq_byname
>>>>>> into platform_get_irq_byname_optional.
>>>>>
>>>>> What is duplicate error information?
>>>>
>>>> The function platform_get_irq_byname print:
>>>> " dev_err(&dev->dev, "IRQ %s not found\n", name);" if error occurred.
>>>>
>>>> In core.c we have the another error message below invoking this function.
>>>> e.g
>>>> 	if (cdns->dev_irq < 0)
>>>> 		dev_err(dev, "couldn't get peripheral irq\n");
>>>>
>>>> So, it's looks like one dev_err is  redundant.
>>>
>>> If we want all 3 IRQs to be valid irrespective of dr_mode then we should
>>> use platform_get_irq_byname() and error out in probe if (ret < 0 && ret != -EPROBE_DEFER).
>>>
>>> We can get rid of the irq check and duplicate error message in other places.
>>
>> To be sure we understand each other correctly.
>>
>> Are You suggesting  to leave the  platform_get_irq_byname()
>> and rid of from core.c the following lines :
>>
>> if (cdns->dev_irq < 0)
>> 	dev_err(dev, "couldn't get peripheral irq\n");
>>
>> and
>>
>> dev_err(dev, "couldn't get otg irq\n");
>> ?
>
>Yes.
>
>>
>> A word of explanation why this patch has been sent.
>> During reviewing the cdnsp driver Chunfeng Yun add such comment:
>>
>> "
>>> +	cdns->dev_irq = platform_get_irq_byname(pdev, "peripheral");
>>> +	if (cdns->dev_irq == -EPROBE_DEFER)
>>> +		return cdns->dev_irq;
>>> +
>>> +	if (cdns->dev_irq < 0)
>>> +		dev_err(dev, "couldn't get peripheral irq\n");
>> Use platform_get_irq_byname_optional? otherwise no need print this log,
>> platform_get_irq_byname() will print it.
>> "
>>
>> In this patch I've chosen the platform_get_irq_byname_optional because both
>> function do the same but the error message from core.c tell us little more then
>> generic message from platform_get_irq_byname.
>
>Using platform_get_irq_byname_optional() says driver expects it is optional but
>only to fail later. It will be confusing to new reader that's all. I leave it to
>you to decide what approach to take.

Thanks for clarification. 
I will send  new patch with platform_get_irq_byname.

Cheers,
Pawel

>
>>>
>>>>
>>>>>
>>>>>>
>>>>>> A change was suggested during reviewing CDNSP driver by Chunfeng Yun.
>>>>>>
>>>>>> Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
>>>>>> ---
>>>>>>     drivers/usb/cdns3/core.c | 4 ++--
>>>>>>     1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>>>>>> index a0f73d4711ae..a3f6dc44cf3a 100644
>>>>>> --- a/drivers/usb/cdns3/core.c
>>>>>> +++ b/drivers/usb/cdns3/core.c
>>>>>> @@ -465,7 +465,7 @@ static int cdns3_probe(struct platform_device *pdev)
>>>>>>
>>>>>>     	cdns->xhci_res[1] = *res;
>>>>>>
>>>>>> -	cdns->dev_irq = platform_get_irq_byname(pdev, "peripheral");
>>>>>> +	cdns->dev_irq = platform_get_irq_byname_optional(pdev, "peripheral");
>>>>>
>>>>> As per DT binding document, these are mandatory properties
>>>>
>>>> I think that name platform_get_irq_byname_optional is little confusing.
>>>> Function descriptions show that both are almost identical:
>>>> /**
>>>>    * platform_get_irq_byname_optional - get an optional IRQ for a device by name
>>>>    * @dev: platform device
>>>>    * @name: IRQ name
>>>>    *
>>>>    * Get an optional IRQ by name like platform_get_irq_byname(). Except that it
>>>>    * does not print an error message if an IRQ can not be obtained.
>>>>    *
>>>>    * Return: non-zero IRQ number on success, negative error number on failure.
>>>>    */
>>>>
>>>>>
>>>>>    - interrupts: Interrupts used by cdns3 controller:
>>>>>           "host" - interrupt used by XHCI driver.
>>>>>           "peripheral" - interrupt used by device driver
>>>>>           "otg" - interrupt used by DRD/OTG  part of driver
>>>>>
>>>>> for dr_mode == "otg" -> all 3 are mandatory.
>>>>> for dr_mode == "host" -> "otg" and "peripheral" IRQs are not required.
>>>>> for dr_mode == "periphearal" -> "otg" and "host" IRQs are not required.
>>>>>
>>>>>>     	if (cdns->dev_irq == -EPROBE_DEFER)
>>>>>>     		return cdns->dev_irq;
>>>>>>
>>>>>> @@ -477,7 +477,7 @@ static int cdns3_probe(struct platform_device *pdev)
>>>>>>     		return PTR_ERR(regs);
>>>>>>     	cdns->dev_regs	= regs;
>>>>>>
>>>>>> -	cdns->otg_irq = platform_get_irq_byname(pdev, "otg");
>>>>>> +	cdns->otg_irq = platform_get_irq_byname_optional(pdev, "otg");
>>>>>>     	if (cdns->otg_irq == -EPROBE_DEFER)
>>>>>>     		return cdns->otg_irq;
>>>>>>
>>>>>>
>>>>>
>>>>
>>>> Regards,
>>>> Pawel
>>>>
>>>
>>> --
>>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>
>--
>Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki