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[2001:1c00:c1e:bf00:1054:9d19:e0f0:8214]) by smtp.gmail.com with ESMTPSA id gl25sm588257ejb.81.2021.10.07.02.54.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 07 Oct 2021 02:54:24 -0700 (PDT) To: Lyude Paul , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org References: <20211001225344.1752203-1-lyude@redhat.com> <2b04c75841f4c1661c242a3371b12d52bb0573ef.camel@redhat.com> From: Hans de Goede Message-ID: <6216276e-6998-cb40-3299-81ac03a1f3a9@redhat.com> Date: Thu, 7 Oct 2021 11:54:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <2b04c75841f4c1661c242a3371b12d52bb0573ef.camel@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hdegoede@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [Nouveau] [Intel-gfx] [PATCH v2 0/4] drm/dp, drm/i915: Finish basic PWM support for VESA backlight helpers 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: , Errors-To: nouveau-bounces@lists.freedesktop.org Sender: "Nouveau" Hi, On 10/5/21 10:26 PM, Lyude Paul wrote: > On Sat, 2021-10-02 at 11:14 +0200, Hans de Goede wrote: >> Hi Lyude, >> >> On 10/2/21 12:53 AM, Lyude Paul wrote: >>> When I originally moved all of the VESA backlight code in i915 into DRM >>> helpers, one of the things I didn't have the hardware or time for >>> testing was machines that used a combination of PWM and DPCD in order to >>> control their backlights. This has since then caused some breakages and >>> resulted in us disabling DPCD backlight support on such machines. This >>> works fine, unless you have a machine that actually needs this >>> functionality for backlight controls to work at all. Additionally, we >>> will need to support PWM for when we start adding support for VESA's >>> product (as in the product of multiplication) control mode for better >>> brightness ranges. >>> >>> So - let's finally finish up implementing basic support for these types >>> of backlights to solve these problems in our DP helpers, along with >>> implementing support for this in i915. And since digging into this issue >>> solved the last questions we really had about probing backlights in i915 >>> for the most part, let's update some of the comments around that as >>> well! >> >> Backlight control is a topic which I'm reasonably familiar with, >> do you want me to review this series for you ? > > Possibly, although I definitely want to make sure that someone from Intel gets > a chance to review this as well. I already expected you would also want someone from Intel to take a look as well :) So to figure out if I have system to test this I ended up taking a close look at the code, which was a nice learning experience. Interesting how some panels use a combination of DCPD + pwm/gpio for enable/disable and/or pwm for brightness level control. I wonder though what DCPD still does if pwm is used for both the enable/disable and brightness-level control ? Since I was taking a close look already I decided to do turn this into a full, the entire set looks good to me: Reviewed-by: Hans de Goede > I'm more curious if you might happen to have > any systems that would be able to test this. I don't believe I have a system where I can test this, The only systems which I have which presumably (I did not check) use eDP / DCPD backlight control are boring ThinkPads with only i915 gfx. Regards, Hans >>> Changes: >>> * Fixup docs >>> * Add patch to stop us from breaking nouveau >>> >>> Lyude Paul (4): >>>   drm/i915: Add support for panels with VESA backlights with PWM >>>     enable/disable >>>   drm/nouveau/kms/nv50-: Explicitly check DPCD backlights for aux >>>     enable/brightness >>>   drm/dp, drm/i915: Add support for VESA backlights using PWM for >>>     brightness control >>>   drm/i915: Clarify probing order in intel_dp_aux_init_backlight_funcs() >>> >>>  drivers/gpu/drm/drm_dp_helper.c               | 75 +++++++++++------ >>>  .../drm/i915/display/intel_dp_aux_backlight.c | 80 ++++++++++++++----- >>>  drivers/gpu/drm/nouveau/nouveau_backlight.c   |  5 +- >>>  include/drm/drm_dp_helper.h                   |  7 +- >>>  4 files changed, 122 insertions(+), 45 deletions(-) >>> >> >