On Wed, Jan 03, 2018 at 10:32:26PM +0100, Jernej Škrabec wrote: > Hi Rob, > > Dne sreda, 03. januar 2018 ob 21:21:54 CET je Rob Herring napisal(a): > > On Sat, Dec 30, 2017 at 10:01:58PM +0100, Jernej Skrabec wrote: > > > This commit adds all necessary compatibles and descriptions needed to > > > implement A83T HDMI pipeline. > > > > > > Mixer is already properly described, so only compatible is added. > > > > > > However, A83T TCON1, which is connected to HDMI, doesn't have channel 0, > > > contrary to all TCONs currently described. Because of that, TCON > > > documentation is extended. > > > > > > A83T features Synopsys DW HDMI controller with a custom PHY which looks > > > like Synopsys Gen2 PHY with few additions. Since there is no > > > documentation, needed properties were found out through experimentation > > > and reading BSP code. > > > > > > At the end, example is added for newer SoCs, which features DE2 and DW > > > HDMI. > > > > > > Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxx> > > > --- > > > > > > .../bindings/display/sunxi/sun4i-drm.txt | 188 > > > ++++++++++++++++++++- 1 file changed, 181 insertions(+), 7 deletions(-) > > > > > > diff --git a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > > b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt index > > > 9f073af4c711..3eca258096a5 100644 > > > --- a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > > +++ b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > > > > > @@ -64,6 +64,40 @@ Required properties: > > > first port should be the input endpoint. The second should be the > > > output, usually to an HDMI connector. > > > > > > +DWC HDMI TX Encoder > > > +----------------------------- > > > + > > > +The HDMI transmitter is a Synopsys DesignWare HDMI 1.4 TX controller IP > > > +with Allwinner's own PHY IP. It supports audio and video outputs and CEC. > > > + > > > +These DT bindings follow the Synopsys DWC HDMI TX bindings defined in > > > +Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt with the > > > +following device-specific properties. > > > + > > > +Required properties: > > > + > > > + - compatible: value must be one of: > > > + * "allwinner,sun8i-a83t-dw-hdmi" > > > + - reg: two pairs of base address and size of memory-mapped region, > > > first > > > + for controller and second for PHY > > > + registers. > > > > Seems like the phy should be a separate node and use the phy binding. > > You can use the phy binding even if you don't use the kernel phy > > framework... > > Unfortunately, it's not so straighforward. Phy is actually accessed through > I2C implemented in HDMI controller. Second memory region in this case has > small influence on phy. However, it has big influence on controller. For > example, magic number has to be written in one register in second memory > region in order to unlock read access to any register from first memory region > (controller). However, they shouldn't be merged to one region, because first > memory region requires byte access while second memory region can be accessed > per byte or word. > > To complicate things more, later I want to add support for another SoC which > has same glue layer (unlocking read access, etc.) and uses memory mapped phy > registers in second memory region. > > I think current binding is the least complicated way to represent this. I agree with Rob here. I did a similar thing for the DSI patches I've sent a few monthes ago and it turned out to not be that difficult, so I'm sure you can come up with something :) Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
