From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752641AbdLMKA2 (ORCPT ); Wed, 13 Dec 2017 05:00:28 -0500 Received: from mail-pg0-f68.google.com ([74.125.83.68]:36927 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752131AbdLMKAW (ORCPT ); Wed, 13 Dec 2017 05:00:22 -0500 X-Google-Smtp-Source: ACJfBouq+QkIuKsVkTHfVQRV82vztY6uPyZyGvs76Q6fuI9uRujeB5YifpN3cdlQRrLGg4h7LoTcHA== Date: Wed, 13 Dec 2017 15:30:19 +0530 From: Viresh Kumar To: Greg Kroah-Hartman Cc: Vincent Guittot , Stephen Boyd , Rajendra Nayak , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, robdclark@gmail.com, s.hauer@pengutronix.de, l.stach@pengutronix.de, shawnguo@kernel.org, fabio.estevam@nxp.com, nm@ti.com, xuwei5@hisilicon.com, robh+dt@kernel.org Subject: Re: [PATCH V4 03/12] drivers: Add boot constraints core Message-ID: <20171213100019.GB3322@vireshk-i7> References: <2868a37e561cab91ba5495a1e14b9548c8e93c3e.1509284255.git.viresh.kumar@linaro.org> <20171213094227.GC13194@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171213094227.GC13194@kroah.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13-12-17, 10:42, Greg Kroah-Hartman wrote: > On Sun, Oct 29, 2017 at 07:18:51PM +0530, Viresh Kumar wrote: > > Some devices are powered ON by the bootloader before the bootloader > > handovers control to Linux. It maybe important for those devices to keep > > working until the time a Linux device driver probes the device and > > reconfigure its resources. > > > > A typical example of that can be the LCD controller, which is used by > > the bootloaders to show image(s) while the platform is booting into > > Linux. The LCD controller can be using some resources, like clk, > > regulators, PM domain, etc, that are shared between several devices. > > These shared resources should be configured to satisfy need of all the > > users. If another device's (X) driver gets probed before the LCD > > controller driver in this case, then it may end up reconfiguring these > > resources to ranges satisfying the current users (only device X) and > > that can make the LCD screen unstable. > > > > This patch introduces the concept of boot-constraints, which will be set > > by the bootloaders and the kernel will satisfy them until the time > > driver for such a device is probed (successfully or unsuccessfully). > > > > The list of boot constraint types is empty for now, and will be > > incrementally updated by later patches. > > > > Only two routines are exposed by the boot constraints core for now: > > I think we need some documentation somewhere on how to use this, right? Will add that in next version. -- viresh