From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752286Ab3AUISQ (ORCPT ); Mon, 21 Jan 2013 03:18:16 -0500 Received: from hqemgate03.nvidia.com ([216.228.121.140]:2760 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751365Ab3AUISO (ORCPT ); Mon, 21 Jan 2013 03:18:14 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Mon, 21 Jan 2013 00:18:02 -0800 From: Alex Courbot To: Thierry Reding CC: Stephen Warren , "linux-fbdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" , Mark Zhang , "gnurou@gmail.com" Subject: Re: [PATCH 0/3] pwm-backlight: add subdrivers & Tegra support Date: Mon, 21 Jan 2013 17:18:11 +0900 Message-ID: <6871054.sK10m5bePf@percival> Organization: NVIDIA User-Agent: KMail/4.9.5 (Linux/3.6.11-1-ARCH; KDE/4.9.5; x86_64; ; ) In-Reply-To: <20130121074928.GE15508@avionic-0098.adnet.avionic-design.de> References: <1358591420-7790-1-git-send-email-acourbot@nvidia.com> <20130121074928.GE15508@avionic-0098.adnet.avionic-design.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thierry, On Monday 21 January 2013 15:49:28 Thierry Reding wrote: > Eventually this should all be covered by the CDF, but since that's not > ready yet we want something ad-hoc to get the hardware supported. As > such I would like to see this go into some sort of minimalistic, Tegra- > specific display/panel framework. I'd prefer to keep the pwm-backlight > driver as simple and generic as possible, that is, a driver for a PWM- > controlled backlight. > > Another advantage of moving this into a sort of display framework is > that it may help in defining the requirements for a CDF and that moving > the code to the CDF should be easier once it is done. > > Last but not least, abstracting away the panel allows other things such > as physical dimensions and display modes to be properly encapsulated. I > think that power-on/off timing requirements for panels also belong to > this set since they are usually specific to a given panel. > > Maybe adding these drivers to tegra-drm for now would be a good option. > That way the corresponding glue can be added without a need for inter- > tree dependencies. IIRC (because that was a while ago already) having a Tegra-only display framework is exactly what we wanted to avoid in the first place. This series does nothing but leverage the callbacks mechanism that already exists in pwm- backlight and make it available to DT systems. If we start making a Tegra- specific solution, then other architectures will have to reinvent the wheel again. I really don't think we want to go that way. These patches only makes slight changes to pwm_bl.c and do not extend its capabilities. I agree that a suitable solution will require the CDF, but by the meantime, let's go for the practical route instead of repeating the same mistakes (i.e. architecture-specific frameworks) again. There are certainly better ways to do this, but I'm not convinced at all that a Tegra-only solution is one of them. Alex.