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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3E79C433EF for ; Fri, 5 Nov 2021 20:25:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AED6F61186 for ; Fri, 5 Nov 2021 20:25:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233525AbhKEU2C (ORCPT ); Fri, 5 Nov 2021 16:28:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233373AbhKEU2B (ORCPT ); Fri, 5 Nov 2021 16:28:01 -0400 Received: from mail-io1-xd33.google.com (mail-io1-xd33.google.com [IPv6:2607:f8b0:4864:20::d33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 453A3C061714 for ; Fri, 5 Nov 2021 13:25:21 -0700 (PDT) Received: by mail-io1-xd33.google.com with SMTP id d70so11123268iof.7 for ; Fri, 05 Nov 2021 13:25:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LrK07k0Lpn9CHC7K58jZi/mGEAzkF+QHwrwjm8onEpQ=; b=J5P2n9oSkKMVEby8FUnF9XKM7m7v29C9QXYnLi8ad3Gc0hFBr8XXUfoBnhnXCvQbCT jjaOYs//TeGM0x1WTuneAjydHwuzeXNZNwzHdKUuZS2sIpjpZ2EB5MdBULXyZcxFH2im KFtNl/2wO/3NMsNLqEPqj3//SqItdZo7l97A0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LrK07k0Lpn9CHC7K58jZi/mGEAzkF+QHwrwjm8onEpQ=; b=43+rKvpDUgQ8qcK6a8UtFY547mzvJgLXsICFYtHk5LrY0Fdc6RozvS9Rpa4/Ezw56f o3eKG0wWISkqhyZ0RaSWwHUYFqV3P1fS627Zb8yZ3MlEnvZ9wv7cIIM+Pe81KWIu7bC4 V16OJ2TJDb9V2/MFEF5keUQy1bm+bBX9UhlxS+iimk0uYoFkYtzlmHhqSJFaSdlXeCaT W5x0GYnGaUj6gPRu1vUEqdPpHlGHYOLTpzd+JHGRa+QIviDngeklIrs3y489h3rtLfN0 3fmiA3TBKxv4ZjENmVg+wAM+OIVKe+1OYMMNG8gbJIVf6p3ZpCT5tLUVLqUP/+axPdly +gxA== X-Gm-Message-State: AOAM530WNb3HFBtCTObuo/LA5p8GR1JOcTwXUzPmAWcmmp2jXxtTjaFE q9Nkcv3ayA9/K+tvzE990vN3uGbEiR/3mw== X-Google-Smtp-Source: ABdhPJwkYCzOoyTghHLNVnCVOhZl+51oXbC96pJiOUMKc/zwiAW5j5+uvgbN7eEtQeQ2dwo6jzbY9A== X-Received: by 2002:a05:6638:2113:: with SMTP id n19mr11076757jaj.8.1636143920453; Fri, 05 Nov 2021 13:25:20 -0700 (PDT) Received: from mail-il1-f182.google.com (mail-il1-f182.google.com. [209.85.166.182]) by smtp.gmail.com with ESMTPSA id d7sm3541179ioh.0.2021.11.05.13.25.19 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Nov 2021 13:25:19 -0700 (PDT) Received: by mail-il1-f182.google.com with SMTP id y17so10656258ilb.9 for ; Fri, 05 Nov 2021 13:25:19 -0700 (PDT) X-Received: by 2002:a05:6e02:1a67:: with SMTP id w7mr35042875ilv.165.1636143919429; Fri, 05 Nov 2021 13:25:19 -0700 (PDT) MIME-Version: 1.0 References: <20211105183342.130810-1-lyude@redhat.com> <20211105183342.130810-4-lyude@redhat.com> In-Reply-To: <20211105183342.130810-4-lyude@redhat.com> From: Doug Anderson Date: Fri, 5 Nov 2021 13:25:08 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 3/5] drm/dp: Don't read back backlight mode in drm_edp_backlight_enable() To: Lyude Paul Cc: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, Thomas Zimmermann , David Airlie , open list , Rodrigo Vivi Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, Nov 5, 2021 at 11:34 AM Lyude Paul wrote: > > As it turns out, apparently some machines will actually leave additional > backlight functionality like dynamic backlight control on before the OS > loads. Currently we don't take care to disable unsupported features when > writing back the backlight mode, which can lead to some rather strange > looking behavior when adjusting the backlight. > > So, let's fix this by just not reading back the current backlight mode on > initial enable. I don't think there should really be any downsides to this, > and this will ensure we don't leave any unsupported functionality enabled. > > This should fix at least one (but not all) of the issues seen with DPCD > backlight support on fi-bdw-samus > > v5: > * Just avoid reading back DPCD register - Doug Anderson > > Signed-off-by: Lyude Paul > Fixes: 867cf9cd73c3 ("drm/dp: Extract i915's eDP backlight code into DRM helpers") > --- > drivers/gpu/drm/drm_dp_helper.c | 40 ++++++++++----------------------- > 1 file changed, 12 insertions(+), 28 deletions(-) You forgot to CC me on this one! ;-) This looks good to me now, so FWIW: Reviewed-by: Douglas Anderson