Re: [PATCH v2] backlight: pwm: reject legacy pwm request for device defined in dt

[Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>]

On 12.10.2015 18:19, Boris Brezillon wrote:
> On Mon, 12 Oct 2015 17:19:35 +0300
> Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> wrote:
>>
>>> Thierry's patch makes sure that EPROBE_DEFER is not returned when the
>>> PWM device definition is not found using in the PWM lookup tables or
>>> the DT definition,
>>
>> This is okay, but I'm interested in proper handling of cases other than
>> EPROBE_DEFER. EPROBE_DEFER and the related issues are on your balance
>> and I'm attempting to avoid interfering with it here :)
> 
> I keep thinking we should fix all platforms using the ->pwm_id pdata
> field to attach a PWM device to a PWM backlight instead of trying to
> guess when falling back to the legacy API is acceptable...
> 
>>
>>> and in this case the pwm_bl code will fallback to
>>> the legacy PWM API, which AFAICT is what you're trying to solve.
>>
>> Fallback must happen exclusively under (IS_ERR(pb->pwm) &&
>> PTR_ERR(pb->pwm) != -EPROBE_DEFER && !pdev->dev.of_node) condition IMHO.
>>
>> Before EPROBE_DEFER appeared on the scene the condition was
>> (IS_ERR(pb->pwm) && !pdev->dev.of_node).
>>
>> So, the question is if my change requires any updates or not from your
>> point of view.
> 
> ... but from a functional point of view your patch seems correct.

Sounds good, thank you for review.


Robert,

because you found a regression in the related area of code on a
platform, which uses legacy PWM API, could you please confirm that three
patches applied in a row don't break anything for you, the changes are:

* Nicolas' 68feaca0b1 ("backlight: pwm: Handle EPROBE_DEFER while
requesting the PWM")
* Thierry' https://lkml.org/lkml/2015/10/5/319
* and this one is the last in the series:
http://thread.gmane.org/gmane.linux.pwm/2813

--
With best wishes,
Vladimir