From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Zapolskiy Subject: Re: [PATCH 1/2] backlight: pwm: don't call legacy pwm request for device defined in dt Date: Wed, 21 Jan 2015 15:18:37 +0200 Message-ID: <54BFA72D.5040006@mentor.com> References: <1413035186-11771-1-git-send-email-vladimir_zapolskiy@mentor.com> <1413035186-11771-2-git-send-email-vladimir_zapolskiy@mentor.com> <20141107134848.GB31950@ulmo> <545CD4DC.4030409@mentor.com> <545CDDF5.70905@mentor.com> <547C7F8A.40707@mentor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from relay1.mentorg.com ([192.94.38.131]:46452 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517AbbAUNSt (ORCPT ); Wed, 21 Jan 2015 08:18:49 -0500 In-Reply-To: <547C7F8A.40707@mentor.com> Sender: linux-pwm-owner@vger.kernel.org List-Id: linux-pwm@vger.kernel.org To: Thierry Reding Cc: linux-fbdev@vger.kernel.org, linux-pwm@vger.kernel.org, Jingoo Han , Bryan Wu , Lee Jones Hello Thierry, On 01.12.2014 16:47, Vladimir Zapolskiy wrote: > Hello Thierry, > > On 07.11.2014 16:57, Vladimir Zapolskiy wrote: >> Thierry, >> >> On 07.11.2014 16:19, Vladimir Zapolskiy wrote: >>> Hi Thierry, >>> >>> On 07.11.2014 15:48, Thierry Reding wrote: >>>> On Sat, Oct 11, 2014 at 04:46:25PM +0300, Vladimir Zapolskiy wrote: >>>>> Platform PWM backlight data provided by board's device tree should be >>>>> complete enough to successfully request a pwm device using pwm_get() API. >>>>> >>>>> Based on initial implementation done by Dmitry Eremin-Solenikov. >>>>> >>>>> Reported-by: Dmitry Eremin-Solenikov >>>>> Signed-off-by: Vladimir Zapolskiy >>>>> Cc: Thierry Reding >>>>> Cc: Jingoo Han >>>>> Cc: Bryan Wu >>>>> Cc: Lee Jones >>>>> --- >>>>> drivers/video/backlight/pwm_bl.c | 14 +++++++------- >>>>> 1 file changed, 7 insertions(+), 7 deletions(-) >>>> >>>> I don't really understand what this is supposed to do. The commit >>>> message doesn't make a very good job of explaining it either. >>>> >>>> Can you describe in more detail what problem this fixes and why it >>>> should be merged? >>> >>> thank you for review. >>> >>> As it is shown by the code this particular change rejects fallback to >>> legacy PWM device request (which itself in turn is fixed in the next >>> commit) for boards with supplied DTS, "pwm-backlight" compatible node >>> and unregistered corresponding PWM device in that node. >>> >>> I don't know if there is a good enough reason to register PWM backlight >>> device connected to some quite arbitrary PWM device, if no PWM device >>> information is given in the "pwm-backlight" compatible node, so I think >>> it makes sense to change the default policy. >>> >> >> also please note that >> Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt >> quite fairly describes "pwms" as a required property, but right now this >> statement from the documentation is wrong, it is possible to register >> pwm-backlight device driver (using notorious pwm_request() legacy API) >> connected to some unspecified pwm device. >> >> I don't think that the current registration policy is correct, that's >> why I propose to fix the logic instead of making a documentation update. >> > > have you had a chance to check the rationale of the change? > > If you accept it, should I make the commit message more verbose? any updates? Do you have plans to merge the change? -- With best wishes, Vladimir