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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 D7BF7C43142 for ; Thu, 2 Aug 2018 10:18:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7988E21501 for ; Thu, 2 Aug 2018 10:18:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7988E21501 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731362AbeHBMIb (ORCPT ); Thu, 2 Aug 2018 08:08:31 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:48637 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726977AbeHBMIb (ORCPT ); Thu, 2 Aug 2018 08:08:31 -0400 Received: from lupine.hi.pengutronix.de ([2001:67c:670:100:3ad5:47ff:feaf:1a17] helo=lupine) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1flAg7-0003BA-A9; Thu, 02 Aug 2018 12:17:55 +0200 Message-ID: <1533205073.3516.17.camel@pengutronix.de> Subject: Re: [PATCH v2] drm/mxsfb: Fix runtime PM for unpowering lcdif block From: Philipp Zabel To: Leonard Crestez , "stefan@agner.ch" , "marex@denx.de" , "shawnguo@kernel.org" Cc: Anson Huang , "airlied@linux.ie" , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Fabio Estevam , dl-linux-imx , "kernel@pengutronix.de" , Robert Chiras , "l.stach@pengutronix.de" Date: Thu, 02 Aug 2018 12:17:53 +0200 In-Reply-To: References: <1533038097.3444.13.camel@pengutronix.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-07-31 at 12:17 +0000, Leonard Crestez wrote: > On Tue, 2018-07-31 at 13:54 +0200, Philipp Zabel wrote: > > On Tue, 2018-07-17 at 13:48 +0300, Leonard Crestez wrote: > > > Adding lcdif nodes to a power domain currently does work, it results in > > > black/corrupted screens or hangs. While the driver does enable runtime > > > pm it does not deal correctly with the block being unpowered. > > > > > > Ensure power is on when required by adding pm_runtime_get/put_sync to > > > mxsfb_pipe_enable/disable. > > > > > > Since power is lost on suspend implement PM_SLEEP_OPS using > > > drm_mode_config_helper_suspend/resume. > > > > > > The mxsfb_plane_atomic_update function can get called before > > > mxsfb_pipe_enable while the block is not yet powered. When this happens > > > the write to LCDIF_NEXT_BUF is lost causing corrupt display on unblank > > > until a refresh. > > > > Why does this happen? > > I'm not sure what you're asking but register writes to unpowered or > unclocked blocks are not expected to "just work". Here the write is > ignored/lost but I think on imx8 it can even cause a bus error. > > The approach here is to only set the framebuffer address as part of > activating the display. I wonder why atomic update is called at all while the pipe is not enabled. regards Philipp