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[209.85.166.180]) by smtp.gmail.com with ESMTPSA id b4sm4553901iot.45.2021.11.05.13.25.19 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-f180.google.com with SMTP id j28so10662015ila.1 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: To: Lyude Paul Content-Type: text/plain; charset="UTF-8" Subject: Re: [Nouveau] [PATCH v5 3/5] drm/dp: Don't read back backlight mode in drm_edp_backlight_enable() X-BeenThere: nouveau@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Nouveau development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Airlie , nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, open list , dri-devel@lists.freedesktop.org, Rodrigo Vivi Errors-To: nouveau-bounces@lists.freedesktop.org Sender: "Nouveau" 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