From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH 3/7] drm/sun4i: Add SAT and DRC drivers Date: Tue, 6 Sep 2016 15:59:39 +0200 Message-ID: <20160906135939.GF9040@lukather> References: <20160901153204.11217-1-maxime.ripard@free-electrons.com> <20160901153204.11217-4-maxime.ripard@free-electrons.com> <8737lfwhz9.fsf@dell.be.48ers.dk> Reply-To: maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="cpvLTH7QU4gwfq3S" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: <8737lfwhz9.fsf-D6SC8u56vOOJDPpyT6T3/w@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Peter Korsgaard Cc: Daniel Vetter , David Airlie , Thierry Reding , Chen-Yu Tsai , Rob Herring , dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Thomas Petazzoni List-Id: dri-devel@lists.freedesktop.org --cpvLTH7QU4gwfq3S Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Hi Peter, On Sun, Sep 04, 2016 at 10:03:06PM +0200, Peter Korsgaard wrote: > >>>>> "Maxime" == Maxime Ripard writes: > > Hi, > > > The A33 pipeline also has some new components called SAT and DRC. Even > > though their exact features and programming model is not known (or > > documented), they need to be clocked for the pipeline to carry the video > > signal all the way. > > > Add minimal drivers for those that just claim the needed resources for the > > pipeline to operate properly. > > > Signed-off-by: Maxime Ripard > > --- > > .../bindings/display/sunxi/sun4i-drm.txt | 37 +++++++ > > drivers/gpu/drm/sun4i/Makefile | 3 +- > > drivers/gpu/drm/sun4i/sun6i_drc.c | 117 +++++++++++++++++++++ > > drivers/gpu/drm/sun4i/sun8i_sat.c | 105 ++++++++++++++++++ > > 4 files changed, 261 insertions(+), 1 deletion(-) > > create mode 100644 drivers/gpu/drm/sun4i/sun6i_drc.c > > create mode 100644 drivers/gpu/drm/sun4i/sun8i_sat.c > > > diff --git a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > index d467ea93ac08..87c3c8dd34cb 100644 > > --- a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > +++ b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > @@ -51,6 +51,43 @@ Required properties: > > second the block connected to the TCON channel 1 (usually the TV > > encoder) > > > +SAT > > +--- > > + > > +The SAT, found in the A33, allows to do some color correction. > > + > > +Required properties: > > + - compatible: value must be one of: > > + * allwinner,sun8i-a33-sat > > + - reg: base address and size of the memory-mapped region. > > + - clock: phandles to bus clock feeding the SAT > > + - resets: phandles to the reset line driving the SAT > > + > > +- ports: A ports node with endpoint definitions as defined in > > + Documentation/devicetree/bindings/media/video-interfaces.txt. The > > + first port should be the input endpoints, the second one the outputs > > + > > +DRC > > +--- > > + > > +The DRC, found in the latest Allwinner SoCs (A31, A23, A33), allows to > > +do some backlight control to enhance the power consumption. > > 'Enhance the power consumption'? That doesn't sound like something you > would want ;) Presumably it is something to allow you to save power by > dynamically adjusting LCD backlight and pixel brightness/contrast > depending on screen content? I believe this is typically called content > adaptive backlight control: > > https://www.ecnmag.com/article/2010/04/content-adaptive-lcd-backlight-control > > You spell out what DRC and SAT stands for in the driver source code, > perhaps it also makes sense to do it here? > > Perhaps rewording it to something like this is clearer: > > .. allows to dynamically adjust pixel brightness/contrast based on > histogram measurements for LCD content adaptive backlight control. You're right, I changed it. Thanks! Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com --cpvLTH7QU4gwfq3S--