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Message-ID: <20141006180217.3b98a67e@bbrezillon> Date: Mon, 6 Oct 2014 18:02:17 +0200 From: Boris Brezillon <boris.brezillon@...e-electrons.com> To: Thierry Reding <thierry.reding@...il.com> Cc: David Airlie <airlied@...ux.ie>, dri-devel@...ts.freedesktop.org, Nicolas Ferre <nicolas.ferre@...el.com>, Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>, Alexandre Belloni <alexandre.belloni@...e-electrons.com>, Andrew Victor <linux@...im.org.za>, Samuel Ortiz <sameo@...ux.intel.com>, Lee Jones <lee.jones@...aro.org>, linux-pwm@...r.kernel.org, Rob Clark <robdclark@...il.com>, linux-arm-kernel@...ts.infradead.org, Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>, Mark Rutland <mark.rutland@....com>, Ian Campbell <ijc+devicetree@...lion.org.uk>, Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, Mark Yao <mark.yao@...k-chips.com> Subject: Re: [PATCH v7 06/11] drm: add DT bindings documentation for atmel-hlcdc-dc driver On Mon, 6 Oct 2014 16:26:10 +0200 Thierry Reding <thierry.reding@...il.com> wrote: > On Mon, Oct 06, 2014 at 03:53:58PM +0200, Boris Brezillon wrote: > > On Mon, 6 Oct 2014 14:35:06 +0200 > > Thierry Reding <thierry.reding@...il.com> wrote: > > > > > On Mon, Oct 06, 2014 at 02:14:40PM +0200, Boris Brezillon wrote: > > > > On Mon, 6 Oct 2014 12:54:34 +0200 > > > > Thierry Reding <thierry.reding@...il.com> wrote: > > > > > > > > > On Wed, Oct 01, 2014 at 04:53:03PM +0200, Boris Brezillon wrote: > > > > > > From: Boris BREZILLON <boris.brezillon@...e-electrons.com> > > > > > > > > > > > > The Atmel HLCDC (HLCD Controller) IP available on some Atmel SoCs (i.e. > > > > > > at91sam9n12, at91sam9x5 family or sama5d3 family) provides a display > > > > > > controller device. > > > > > > > > > > > > The HLCDC block provides a single RGB output port, and only supports LCD > > > > > > panels connection to LCD panels for now. > > > > > > > > > > > > The atmel,panel property link the HLCDC RGB output with the LCD panel > > > > > > connected on this port (note that the HLCDC RGB connector implementation > > > > > > makes use of the DRM panel framework). > > > > > > > > > > > > Connection to other external devices (DRM bridges) might be added later by > > > > > > mean of a new atmel,xxx (atmel,bridge) property. > > > > > > > > > > > > Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com> > > > > > > --- > > > > > > .../devicetree/bindings/drm/atmel-hlcdc-dc.txt | 53 ++++++++++++++++++++++ > > > > > > 1 file changed, 53 insertions(+) > > > > > > create mode 100644 Documentation/devicetree/bindings/drm/atmel-hlcdc-dc.txt > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/drm/atmel-hlcdc-dc.txt b/Documentation/devicetree/bindings/drm/atmel-hlcdc-dc.txt > > > > > > new file mode 100644 > > > > > > index 0000000..ebc1a91 > > > > > > --- /dev/null > > > > > > +++ b/Documentation/devicetree/bindings/drm/atmel-hlcdc-dc.txt > > > > > > @@ -0,0 +1,53 @@ > > > > > > +Device-Tree bindings for Atmel's HLCDC (High LCD Controller) DRM driver > > > > > > + > > > > > > +The Atmel HLCDC Display Controller is subdevice of the HLCDC MFD device. > > > > > > +See ../mfd/atmel-hlcdc.txt for more details. > > > > > > + > > > > > > +Required properties: > > > > > > + - compatible: value should be "atmel,hlcdc-display-controller" > > > > > > + - pinctrl-names: the pin control state names. Should contain "default". > > > > > > + - pinctrl-0: should contain the default pinctrl states. > > > > > > + - #address-cells: should be set to 1. > > > > > > + - #size-cells: should be set to 0. > > > > > > + > > > > > > +Required children nodes: > > > > > > + Children nodes are encoding available output ports and their connections > > > > > > + to external devices using the OF graph reprensentation (see ../graph.txt). > > > > > > + At least one port node is required. > > > > > > > > > > Are the connections configurable at runtime? Does the SoC have IP blocks > > > > > for HDMI or other types of outputs or does it provide only RGB output to > > > > > external blocks? > > > > > > > > No, there's only one RGB output port, but you can connect more than one > > > > device on the RGB port (should we call it DPI port ?). > > > > Actually Atmel connected an HDMI encoder and an LCD panel connected on > > > > the same port on their dev kit. > > > > > > This was discussed in some other thread if I remember correctly. I still > > > think that the HLCDC node should only contain a single output, no matter > > > how many encoders or panels get connected. > > > > > > So the output represents the set of signals that exit the IP block, but > > > what's connected to them on the board is a board-level detail and > > > therefore should go into the board DTS. > > > > > > In the above case of the Atmel devkit, is there any way to control where > > > the signal goes or does it just go to both the panel and HDMI encoder at > > > the same time and it's up to the user to properly configure the output > > > in order to get either HDMI or panel to display anything? > > > > No there's no way to control where the signal goes. > > What you can control though, is the activation of the associated > > encoder/connectors connected on this bus (using dpms). > > But the bus is really only the CRTC, so using DPMS for this is not how > it's usually done in DRM. Can't you model both outputs as separate > encoders and then attach them to the CRTC? This should work > automatically for the framebuffer console and any userspace that can > talk KMS. That's exactly what I'm proposing, except there's a layer in between handling the video bus format configuration. I just sent you an RFC, proposing an implementation of the DPI/raw-RGB bus layer. > > Perhaps that's already what's being done and I misunderstand what you're > saying. I should go back to reviewing the DRM driver. I started this > morning, then got interrupted by other things. No problem. I'm glad to see that things are eventually moving on. -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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