On Mon, Jun 04, 2018 at 05:09:56PM +0200, Jernej Škrabec wrote: > Dne ponedeljek, 04. junij 2018 ob 13:50:34 CEST je Maxime Ripard napisal(a): > > On Fri, Jun 01, 2018 at 09:19:43AM -0700, Chen-Yu Tsai wrote: > > > On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard > wrote: > > > > On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote: > > > >> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a): > > > >> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote: > > > >> > > >> > > + if (tcon->quirks->needs_tcon_top) { > > > >> > > >> > > + struct device_node *np; > > > >> > > >> > > + > > > >> > > >> > > + np = of_parse_phandle(dev->of_node, > > > >> > > >> > > "allwinner,tcon-top", > > > >> > > >> > > 0); > > > >> > > >> > > + if (np) { > > > >> > > >> > > + struct platform_device *pdev; > > > >> > > >> > > + > > > >> > > >> > > + pdev = of_find_device_by_node(np); > > > >> > > >> > > + if (pdev) > > > >> > > >> > > + tcon->tcon_top = > > > >> > > >> > > platform_get_drvdata(pdev); > > > >> > > >> > > + of_node_put(np); > > > >> > > >> > > + > > > >> > > >> > > + if (!tcon->tcon_top) > > > >> > > >> > > + return -EPROBE_DEFER; > > > >> > > >> > > + } > > > >> > > >> > > + } > > > >> > > >> > > + > > > >> > > >> > > > > >> > > >> > I might have missed it, but I've not seen the bindings > > > >> > > >> > additions for > > > >> > > >> > that property. This shouldn't really be done that way anyway, > > > >> > > >> > instead > > > >> > > >> > of using a direct phandle, you should be using the of-graph, > > > >> > > >> > with the > > > >> > > >> > TCON-top sitting where it belongs in the flow of data. > > > >> > > >> > > > >> > > >> Just to answer to the first question, it did describe it in > > > >> > > >> "[PATCH > > > >> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline". > > > >> > > >> > > > >> > > >> As why I designed it that way - HW representation could be > > > >> > > >> described > > > >> > > >> that way> >> > > > >> > > >> > > > >> > > >> (ASCII art makes sense when fixed width font is used to view > it): > > > >> > > >> / LCD0/LVDS0 > > > >> > > >> > > > >> > > >> / TCON-LCD0 > > > >> > > >> > > > >> > > >> | \ MIPI DSI > > > >> > > >> > > > >> > > >> mixer0 | > > > >> > > >> > > > >> > > >> \ / TCON-LCD1 - LCD1/LVDS1 > > > >> > > >> > > > >> > > >> TCON-TOP > > > >> > > >> > > > >> > > >> / \ TCON-TV0 - TVE0/RGB > > > >> > > >> > > > >> > > >> mixer1 | \ > > > >> > > >> > > > >> > > >> | TCON-TOP - HDMI > > > >> > > >> | > > > >> > > >> | / > > > >> > > >> > > > >> > > >> \ TCON-TV1 - TVE1/RGB > > > >> > > >> > > > >> > > >> This is a bit simplified, since there is also TVE-TOP, which is > > > >> > > >> responsible > > > >> > > >> for sharing 4 DACs between both TVE encoders. You can have two > > > >> > > >> TV outs > > > >> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It > > > >> > > >> even > > > >> > > >> seems that you can arbitrarly choose which DAC is responsible > > > >> > > >> for > > > >> > > >> which signal, so there is a ton of possible end combinations, > > > >> > > >> but I'm > > > >> > > >> not 100% sure. > > > >> > > >> > > > >> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 > > > >> > > >> manual > > > >> > > >> suggest more possibilities, although some of them seem wrong, > > > >> > > >> like RGB > > > >> > > >> feeding from LCD TCON. That is confirmed to be wrong when > > > >> > > >> checking BSP > > > >> > > >> code. > > > >> > > >> > > > >> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, > > > >> > > >> TVE1 and > > > >> > > >> LCD1 for pin muxing, although I'm not sure why is that needed at > > > >> > > >> all, > > > >> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are > > > >> > > >> dedicated and > > > >> > > >> not on PORT D and PORT H, respectively, as TCON-TOP > > > >> > > >> documentation > > > >> > > >> suggest. However, HSYNC and PSYNC lines might be shared between > > > >> > > >> TVE > > > >> > > >> (when it works in RGB mode) and LCD. But that is just my guess > > > >> > > >> since > > > >> > > >> I'm not really familiar with RGB and LCD interfaces. > > > >> > > >> > > > >> > > >> I'm really not sure what would be the best representation in > > > >> > > >> OF-graph. > > > >> > > >> Can you suggest one? > > > >> > > > > > > >> > > > Rob might disagree on this one, but I don't see anything wrong > > > >> > > > with > > > >> > > > having loops in the graph. If the TCON-TOP can be both the input > > > >> > > > and > > > >> > > > output of the TCONs, then so be it, and have it described that > > > >> > > > way in > > > >> > > > the graph. > > > >> > > > > > > >> > > > The code is already able to filter out nodes that have already > > > >> > > > been > > > >> > > > added to the list of devices we need to wait for in the component > > > >> > > > framework, so that should work as well. > > > >> > > > > > > >> > > > And we'd need to describe TVE-TOP as well, even though we don't > > > >> > > > have a > > > >> > > > driver for it yet. That will simplify the backward compatibility > > > >> > > > later > > > >> > > > on. > > > >> > > > > > >> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer > > > >> > > that > > > >> > > binds everything together, and provides signal routing, kind of > > > >> > > like > > > >> > > DE-TOP on A64. So the signal mux controls that were originally > > > >> > > found > > > >> > > in TCON0 and TVE0 were moved out. > > > >> > > > > > >> > > The driver needs to know about that, but the graph about doesn't > > > >> > > make > > > >> > > much sense directly. Without looking at the manual, I understand it > > > >> > > to > > > >> > > likely be one mux between the mixers and TCONs, and one between the > > > >> > > TCON-TVs and HDMI. Would it make more sense to just have the graph > > > >> > > connections between the muxed components, and remove TCON-TOP from > > > >> > > it, like we had in the past? A phandle could be used to reference > > > >> > > the TCON-TOP for mux controls, in addition to the clocks and > > > >> > > resets. > > > >> > > > > > >> > > For TVE, we would need something to represent each of the output > > > >> > > pins, > > > >> > > so the device tree can actually describe what kind of signal, be it > > > >> > > each component of RGB/YUV or composite video, is wanted on each > > > >> > > pin, > > > >> > > if any. This is also needed on the A20 for the Cubietruck, so we > > > >> > > can > > > >> > > describe which pins are tied to the VGA connector, and which one > > > >> > > does > > > >> > > R, G, or B. > > > >> > > > > >> > I guess we'll see how the DT maintainers feel about this, but my > > > >> > impression is that the OF graph should model the flow of data between > > > >> > the devices. If there's a mux somewhere, then the data is definitely > > > >> > going through it, and as such it should be part of the graph. > > > >> > > > >> I concur, but I spent few days thinking how to represent this sanely in > > > >> graph, but I didn't find any good solution. I'll represent here my > > > >> idea and please tell your opinion before I start implementing it. > > > >> > > > >> First, let me be clear that mixer0 and mixer1 don't have same > > > >> capabilities > > > >> (different number of planes, mixer0 supports writeback, mixer1 does > > > >> not, > > > >> etc.). Thus, it does matter which mixer is connected to which > > > >> TCON/encoder. > > > >> mixer0 is meant to be connected to main display and mixer1 to > > > >> auxiliary. That obviously depends on end system. > > > >> > > > >> So, TCON TOP has 3 muxes, which have to be represented in graph. Two of > > > >> them are for mixer/TCON relationship (each of them 1 input and 4 > > > >> possible outputs) and one for TV TCON/HDMI pair selection (2 possible > > > >> inputs, 1 output). > > > >> > > > >> According to current practice in sun4i-drm driver, graph has to have > > > >> port 0, representing input and port 1, representing output. This would > > > >> mean that graph looks something like that: > > > >> > > > >> tcon_top: tcon-top@1c70000 { > > > >> > > > >> compatible = "allwinner,sun8i-r40-tcon-top"; > > > >> ... > > > >> ports { > > > >> > > > >> #address-cells = <1>; > > > >> #size-cells = <0>; > > > >> > > > >> tcon_top_in: port@0 { > > > >> > > > >> #address-cells = <1>; > > > >> #size-cells = <0>; > > > >> reg = <0>; > > > >> > > > >> tcon_top_in_mixer0: endpoint@0 { > > > >> > > > >> reg = <0>; > > > >> remote-endpoint = <&mixer0_out_tcon_top>; > > > >> > > > >> }; > > > >> > > > >> tcon_top_in_mixer1: endpoint@1 { > > > >> > > > >> reg = <1>; > > > >> remote-endpoint = <&mixer1_out_tcon_top>; > > > >> > > > >> }; > > > >> > > > >> tcon_top_in_tcon_tv: endpoint@2 { > > > >> > > > >> reg = <2>; > > > >> // here is HDMI input connection, part of > > > >> board DTS > > > >> remote-endpoint = > > >> to TV TCON output>; > > > >> > > > >> }; > > > >> > > > >> }; > > > >> > > > >> tcon_top_out: port@1 { > > > >> > > > >> #address-cells = <1>; > > > >> #size-cells = <0>; > > > >> reg = <1>; > > > >> > > > >> tcon_top_out_tcon0: endpoint@0 { > > > >> > > > >> reg = <0>; > > > >> // here is mixer0 output connection, part > > > >> of board DTS > > > >> remote-endpoint = > > >> to TCON>; > > > >> > > > >> }; > > > >> > > > >> tcon_top_out_tcon1: endpoint@1 { > > > >> > > > >> reg = <1>; > > > >> // here is mixer1 output connection, part > > > >> of board DTS > > > >> remote-endpoint = > > >> to TCON>; > > > >> > > > >> }; > > > >> > > > >> tcon_top_out_hdmi: endpoint@2 { > > > >> > > > >> reg = <2>; > > > >> remote-endpoint = <&hdmi_in_tcon_top>; > > > >> > > > >> }; > > > >> > > > >> }; > > > >> > > > >> }; > > > >> > > > >> }; > > > > > > > > IIRC, each port is supposed to be one route for the data, so we would > > > > have multiple ports, one for the mixers in input and for the tcon in > > > > output, and one for the TCON in input and for the HDMI/TV in > > > > output. Rob might correct me here. > > Ok, that seems more clean approach. I'll have to extend graph traversing > algorithm in sun4i_drv.c, but that's no problem. > > Just to be clear, you have in mind 3 pairs of ports (0/1 for mixer0 mux, 2/3 > for mixer1 and 4/5 for HDMI input), right? That way each mux is represented > with one pair of ports, even numbered for input and odd numbered for output. Yep, unless Rob feels otherwise. Maxime -- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com