From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751978AbeDIIRI (ORCPT ); Mon, 9 Apr 2018 04:17:08 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:53804 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750952AbeDIIRG (ORCPT ); Mon, 9 Apr 2018 04:17:06 -0400 X-Google-Smtp-Source: AIpwx4+i2qX4XKzyWEOelJVrNwKqnCtT2DXmUtYqsHfIE87ocAtCL6KHoqSln5R8wkBGpRee7Zbaaw== Date: Mon, 9 Apr 2018 09:17:02 +0100 From: Lee Jones To: Enric Balletbo i Serra Cc: Daniel Thompson , Doug Anderson , Pavel Machek , Rob Herring , Jingoo Han , Richard Purdie , Jacek Anaszewski , Brian Norris , Guenter Roeck , Alexandru Stan , linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@collabora.com Subject: Re: [PATCH v3 0/4] backlight: pwm_bl: support linear interpolation and brightness to human eye Message-ID: <20180409081702.rwj773h6ndglnejm@dell> References: <20180208113032.27810-1-enric.balletbo@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180208113032.27810-1-enric.balletbo@collabora.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 08 Feb 2018, Enric Balletbo i Serra wrote: > Dear all, > > This series is a third patchset integrating the requested changes. > > The first and second patch what tries to solve is the problem of > granularity for high resolution PWMs. The idea is simple interpolate > between 2 brightness values so we can have a high PWM duty cycle (a > 16 bits PWM is up to 65535 possible steps) without having to list > out every possible value in the dts. I think that this patch is > required to not break backward compability, to be more flexible and > also extend the functionality to be able to use high resolution PWM > with enough steps to have a good UI experience in userspace. > > The thirth and fourth patch is a bit more ambicious, the idea is let > decide the driver the brightness-levels required in function of the PWM > resolution. To do this create a brightness-levels table filled with the > CIE 1931 algorithm values to convert brightness to PWM duty cycle. > > More detailed info is available in the commit message of every patch. > > Both functionalities were tested on a Samsung Chromebook Plus (that has > a 16 bits PWM) and a SL50 device (with a 8 bits PWM) > > Waiting for your feedback. Looks like you now have some positive feedback. :) Could you please collect all of your received Acks and re-post this set as a [RESEND] please? > Best regards, > > Enric Balletbo i Serra (4): > backlight: pwm_bl: linear interpolation between brightness-levels > dt-bindings: pwm-backlight: add a num-interpolation-steps property. > backlight: pwm_bl: compute brightness of LED linearly to human eye. > dt-bindings: pwm-backlight: move brightness-levels to optional. > > .../bindings/leds/backlight/pwm-backlight.txt | 34 ++- > drivers/video/backlight/pwm_bl.c | 232 +++++++++++++++++++-- > 2 files changed, 246 insertions(+), 20 deletions(-) -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog