From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC45BC31E51 for ; Tue, 18 Jun 2019 07:01:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A04DE20665 for ; Tue, 18 Jun 2019 07:01:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726428AbfFRHBx (ORCPT ); Tue, 18 Jun 2019 03:01:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:45076 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725829AbfFRHBx (ORCPT ); Tue, 18 Jun 2019 03:01:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C7B4FB040; Tue, 18 Jun 2019 07:01:51 +0000 (UTC) Message-ID: <1560841301.21660.9.camel@suse.com> Subject: Re: [IMX] [DRM]: suspend/resume support From: Oliver Neukum To: Pintu Agarwal , open list , linux-arm-kernel@lists.infradead.org, Kernelnewbies , linux-pm@vger.kernel.org Date: Tue, 18 Jun 2019 09:01:41 +0200 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Am Montag, den 17.06.2019, 19:19 +0530 schrieb Pintu Agarwal: > Currently, I am trying to understand what needs to be taken care > during suspend/resume. You need to take care of * wakeup sources * not requiring services of devices higher up in the tree. > With some reference, I figured out that hdmi power off/on needs to be > done during suspend/resume. That would make sense. First of all you need to understand that the generic model is, well, generic. Now this may look like a tautology, so let me explain. A generic model cannot tell you how to save power on a specific hardware. It exists to model dependencies among subsystems and to help you. The suspend() call is a notification which tells you that the rest of the system will not require your services until resume() is called(). That means that after resume() your driver must be functional again. And it means that between suspend() and resume() you cannot touch your device because what is above you in the tree need not be functional. > But after resume, system is hanging. > It seems like vblank events are not getting triggered after the resume. > May be irq remains disabled after resume, I need to figure out some > way to enable the all the irqs again. In your case it looks like parts of dw_hdmi_imx_bind() need to be redone in resume(). HTH Oliver