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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 CB4DFC46475 for ; Thu, 25 Oct 2018 18:08:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9173B20834 for ; Thu, 25 Oct 2018 18:08:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=poorly.run header.i=@poorly.run header.b="ebjoF///" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9173B20834 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=poorly.run 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 S1727772AbeJZCmZ (ORCPT ); Thu, 25 Oct 2018 22:42:25 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:37298 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727588AbeJZCmZ (ORCPT ); Thu, 25 Oct 2018 22:42:25 -0400 Received: by mail-qt1-f193.google.com with SMTP id d14-v6so11000584qto.4 for ; Thu, 25 Oct 2018 11:08:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poorly.run; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=vEEbeX9NEprbLobi7/ZMT/vaCA2hUGeBMovuRomjiIg=; b=ebjoF///WsLO3IeBLxcZg7g0FfZzHZEtaZVMmZ0RHjz0CNGSpbkivhKaMvN41VhysD KiONPbdKufshnU+MO+Qm5t0ZycohZGJ36wKmnmfCe3aK+ms2CRlWDkVn29BPNBsn8Fkg Vj4QFqgGzEW516hSvjP7bE4dxEdL5WqU1GFw2zXlSAEb7ov9A3E7NuIAur9RhPMajX3U Xrueg0BmOhEELS8B6qnm4pqK9KlYeQ9Qm05xEwDaIJhW4idZZxSwfKROTk6PnPBOfPFC z42+sSrmWbE2yGOLcMKL4J/QgfVuYZbO7dnsPWUF2twpFmmfUlBPyayxV6H628pz4yK0 vI5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=vEEbeX9NEprbLobi7/ZMT/vaCA2hUGeBMovuRomjiIg=; b=DgaLnWcdrLLQ6GaX4IPlWWI1NBAXc0VpHqVuSwKrd9MzeTyhtRzZi84dmsgjOReJgx F6Up7Cnax+5hJopN+WWtP+0dZ4IvatT3nXMiOo0/ElJCyqxsBLEYUJCmAx5vPLnbWXei OPTrZKkf+nSURzm0bLm8D5scrBoT0N4ZORqg0VoMaFVkjf1uYJ4fUXQwym4pB/YPVY5B 1Nw1hOhCNyX2yXL8b7zS+yuC33+mhe/BuYqnU1c6g2MoiNtQ/kIxTn6WgeXdeHSLZKke g0RSVw9Xr3XWeeJgKGbfdzkwaOCa8tU5dj5JiSZECO8fBGxHZEoNQSXagp1AnVLW/e7L v+YA== X-Gm-Message-State: AGRZ1gKe4qDzTP+bXSkm8mAjxXqx9KNmRA3mTZjsiIotBEy4OIZNGrWh tnh5O+NLZrETXFKE2KR2+6nphyC6S8gifg== X-Google-Smtp-Source: AJdET5cCqXPlG6AtbmmK+jOFSp5vhRb5P8YakBWpUaCj8AHZ7TzXpoI5No1DA31xcIycd6guK1XmjA== X-Received: by 2002:a0c:fa86:: with SMTP id o6mr292511qvn.148.1540490914622; Thu, 25 Oct 2018 11:08:34 -0700 (PDT) Received: from localhost ([2620:0:1013:11:ad55:b1db:adfe:3b9f]) by smtp.gmail.com with ESMTPSA id u67-v6sm6131148qkh.12.2018.10.25.11.08.34 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 25 Oct 2018 11:08:34 -0700 (PDT) Date: Thu, 25 Oct 2018 14:08:33 -0400 From: Sean Paul To: Douglas Anderson Cc: Sean Paul , Thierry Reding , Sandeep Panda , linux-arm-msm@vger.kernel.org, Laurent Pinchart , jsanka@codeaurora.org, ryandcase@chromium.org, David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/6] drm/panel: simple: Support panels with HPD where HPD isn't connected Message-ID: <20181025180833.GK154160@art_vandelay> References: <20181022204639.8558-1-dianders@chromium.org> <20181022204639.8558-2-dianders@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181022204639.8558-2-dianders@chromium.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 22, 2018 at 01:46:35PM -0700, Douglas Anderson wrote: > Some eDP panels that are designed to be always connected to a board > use their HPD signal to signal that they've finished powering on and > they're ready to be talked to. > > However, for various reasons it's possible that the HPD signal from > the panel isn't actually hooked up. In the case where the HPD isn't > hooked up you can look at the timing diagram on the panel datasheet > and insert a delay for the maximum amount of time that the HPD might > take to come up. > > Let's add support in simple-panel for this concept. > > At the moment we will co-opt the existing "prepare" delay to keep > track of the delay and we'll use a boolean to specify that a given > panel should only apply the delay if the "no-hpd" property was > specified. > > Signed-off-by: Douglas Anderson > --- > > drivers/gpu/drm/panel/panel-simple.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c > index 97964f7f2ace..38c646fb55fd 100644 > --- a/drivers/gpu/drm/panel/panel-simple.c > +++ b/drivers/gpu/drm/panel/panel-simple.c > @@ -63,12 +63,15 @@ struct panel_desc { > * turn the display off (no content is visible) > * @unprepare: the time (in milliseconds) that it takes for the panel > * to power itself down completely > + * @prepare_delay_only_if_no_hpd: The prepare delay should only be done > + * if we know Hot Plug Detect isn't used. I think it'd be more clear if we just had a new 'hpd_absent_delay' which is added to prepare if no_hpd is true. Sean > */ > struct { > unsigned int prepare; > unsigned int enable; > unsigned int disable; > unsigned int unprepare; > + bool prepare_delay_only_if_no_hpd; > } delay; > > u32 bus_format; > @@ -79,6 +82,7 @@ struct panel_simple { > struct drm_panel base; > bool prepared; > bool enabled; > + bool no_hpd; > > const struct panel_desc *desc; > > @@ -215,7 +219,8 @@ static int panel_simple_prepare(struct drm_panel *panel) > > gpiod_set_value_cansleep(p->enable_gpio, 1); > > - if (p->desc->delay.prepare) > + if (p->desc->delay.prepare && > + (!p->desc->delay.prepare_delay_only_if_no_hpd || p->no_hpd)) > msleep(p->desc->delay.prepare); > > p->prepared = true; > @@ -305,6 +310,8 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc) > panel->prepared = false; > panel->desc = desc; > > + panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd"); > + > panel->supply = devm_regulator_get(dev, "power"); > if (IS_ERR(panel->supply)) > return PTR_ERR(panel->supply); > -- > 2.19.1.568.g152ad8e336-goog > -- Sean Paul, Software Engineer, Google / Chromium OS