From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753002AbeCTMNZ (ORCPT ); Tue, 20 Mar 2018 08:13:25 -0400 Received: from mail-qt0-f194.google.com ([209.85.216.194]:45504 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751348AbeCTMNV (ORCPT ); Tue, 20 Mar 2018 08:13:21 -0400 X-Google-Smtp-Source: AG47ELtygq59tunNzm2lAstEdOdjHAYWcFpwW0dWislbGOZOmtqhpHDvOVpI0q9bQzFGkpwQ6nNkNMMv7ykouv/Zeh4= MIME-Version: 1.0 In-Reply-To: <20180320112212.2mwthxug3pu7uqgg@holly.lan> References: <20180208113032.27810-1-enric.balletbo@collabora.com> <20180320112212.2mwthxug3pu7uqgg@holly.lan> From: Enric Balletbo Serra Date: Tue, 20 Mar 2018 13:13:20 +0100 Message-ID: Subject: Re: [PATCH v3 0/4] backlight: pwm_bl: support linear interpolation and brightness to human eye To: Daniel Thompson Cc: Enric Balletbo i Serra , Doug Anderson , Pavel Machek , Rob Herring , Jingoo Han , Richard Purdie , Jacek Anaszewski , Brian Norris , Guenter Roeck , Lee Jones , Alexandru Stan , linux-leds@vger.kernel.org, "devicetree@vger.kernel.org" , linux-kernel , kernel@collabora.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Daniel, 2018-03-20 12:22 GMT+01:00 Daniel Thompson : > On Mon, Mar 19, 2018 at 05:04:31PM +0100, Enric Balletbo Serra wrote: >> Hi Daniel, >> >> Gentle ping for this series, there is any possibility you have a >> chance to review it? Let me know if you want I change something. > > I haven't got it in my TODO backlog... which means either I mistakenly > deleted it when it went through originally or that I deliberately deleted > it because I thought a v4 was coming along soon. > > I could go diving through the archives if I need to but were there other > pending changes for this patchset? > Unless I am missing something there isn't pending changes requested. 1/4 I addressed your latest comments in this version. 2/4 Has been acked by Rob Herring 3/4 I did not receive feedback but iirc we agreed to use a pre-computed table. 4/4 Is already acked by you. Regards, Enric > > Daniel. > > >> >> Thanks, >> Enric >> >> 2018-02-08 12:30 GMT+01:00 Enric Balletbo i Serra >> : >> > 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. >> > >> > 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(-) >> > >> > -- >> > 2.15.1 >> >