# Re: \[PATCH 3/9\] Doc/DT: Add DT binding documentation for DVI Connector - List: linux-fbdev - 5 messages, 4 authors - Page: https://ratatoskr.run/linux-fbdev/2014/03/8087091/t ## Re: \[PATCH 3/9\] Doc/DT: Add DT binding documentation for DVI Connector - From: Rob Herring \ - Date: 2014-03-10 21:45:58 - Message: https://ratatoskr.run/linux-fbdev/2014/03/8087091.md ```text On Fri, Feb 28, 2014 at 10:25 AM, Philipp Zabel [ref] wrote: > Am Freitag, den 28.02.2014, 15:59 +0000 schrieb Russell King - ARM > Linux: >> On Fri, Feb 28, 2014 at 02:20:10PM +0200, Tomi Valkeinen wrote: >> > Add DT binding documentation for DVI Connector. >> > >> > Signed-off-by: Tomi Valkeinen >> > Reviewed-by: Archit Taneja >> > --- >> > .../devicetree/bindings/video/dvi-connector.txt | 26 ++++++++++++++++++++++ >> > 1 file changed, 26 insertions(+) >> > create mode 100644 Documentation/devicetree/bindings/video/dvi-connector.txt >> > >> > diff --git a/Documentation/devicetree/bindings/video/dvi-connector.txt b/Documentation/devicetree/bindings/video/dvi-connector.txt >> > new file mode 100644 >> > index 000000000000..6a0aff866c78 >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/video/dvi-connector.txt >> > @@ -0,0 +1,26 @@ >> > +DVI Connector >> > +======= >> > + >> > +Required properties: >> > +- compatible: "dvi-connector" >> > + >> > +Optional properties: >> > +- label: a symbolic name for the connector >> > +- i2c-bus: phandle to the i2c bus that is connected to DVI DDC >> > + >> > +Required nodes: >> > +- Video port for DVI input >> > + >> > +Example >> > +------- >> > + >> > +dvi0: connector@0 { >> > + compatible = "dvi-connector"; >> > + label = "dvi"; >> > + >> > + i2c-bus = <&i2c3>; >> > + >> > + dvi_connector_in: endpoint { >> > + remote-endpoint = <&tfp410_out>; >> > + }; >> > +}; >> >> This looks far too simplistic. There are different classes of DVI >> connector - there is: >> >> DVI A - analogue only >> DVI D - digital only (single and dual link) >> DVI I - both (single and dual digital link) >> >> DRM at least makes a distinction between these three classes, and this >> disctinction is part of the user API. How would a display system know >> which kind of DVI connector is wired up on the board from this DT >> description? > > Maybe this could be inferred from the sources connected to it. For > example a i.MX5 board with the SoC internal TV Encoder and an external > SiI902x HDMI encoder connected to the same DVI I connector: > > ipu { > port@2 { > ipu_di0_disp0: endpoint { > remote-endpoint = <&sii902x_in>; > }; > }; > port@3 { > ipu_di1_tve: endpoint { > remote-endpoint = <&tve_in>; > }; > }; > }; > > &sii902x { > compatible = "si,sii9022"; > > port@0 { > sii902x_in: endpoint { > remote-endpoint = <&ipu_di0>; > }; > }; > port@1 { > sii902x_out: endpoint { > remote-endpoint = <&dvi_d_in>; > }; > }; > }; > > &tve { > compatible = "fsl,imx53-tve"; > port@0 { > tve_in: endpoint { > remote-endpoint = <&ipu_di1>; > }; > }; > port@1 { > tve_out: endpoint { > remote-endpoint = <&dvi_a_in>; > }; > }; > }; > > dvi-connector { > compatible = "dvi-connector"; > ddc-i2c-bus = <&i2c3>; > > port { > dvi_d_in: endpoint@0 { > remote-endpoint = <&sii902x_out>; > }; > dvi_a_in: endpoint@1 { > remote-endpoint = <&tve_out>; > }; > }; > }; > > It should be possible to let the connector know that those two endpoints > are connected to a TMDS source and to a VGA source, respectively. I like this proposal over the others. Although, would dual link be a single endpoint or 2 endpoints? How would you differentiate that? The port node seems a bit pointless. Rob ``` ## Re: \[PATCH 3/9\] Doc/DT: Add DT binding documentation for DVI Connector - From: Tomi Valkeinen \ - Date: 2014-03-11 06:39:11 - Message: https://ratatoskr.run/linux-fbdev/2014/03/8087113.md ```text On 10/03/14 23:45, Rob Herring wrote: > I like this proposal over the others. Although, would dual link be a I don't like inferring the information. With the above, you can't find out that the DVI connector has digital and analog support before all the drivers are loaded. > single endpoint or 2 endpoints? How would you differentiate that? Hmm, well endpoints for a single port are exclusive. So it's either a single port and a single endpoint, or two ports and two endpoints. I think dual link has to be single port & endpoint, as the TMDS links need to be driven together as a single bus. And dual-link is not really "two links". DVI dual-link means 1 clock lane and 6 data lanes, compared to 1 clock lane and 3 data lanes for single-link. > The port node seems a bit pointless. There's another thread discussing the ports and endpoints. The port node represents, for example, the pins for the connection for that device. And an endpoint-endpoint link represents wires between two ports. Tomi ``` ## Re: \[PATCH 3/9\] Doc/DT: Add DT binding documentation for DVI Connector - From: Geert Uytterhoeven \ - Date: 2014-03-11 08:00:12 - Message: https://ratatoskr.run/linux-fbdev/2014/03/8087117.md ```text On Tue, Mar 11, 2014 at 7:39 AM, Tomi Valkeinen [ref] wrote: > On 10/03/14 23:45, Rob Herring wrote: >> I like this proposal over the others. Although, would dual link be a > > I don't like inferring the information. With the above, you can't find > out that the DVI connector has digital and analog support before all the > drivers are loaded. > >> single endpoint or 2 endpoints? How would you differentiate that? > > Hmm, well endpoints for a single port are exclusive. So it's either a > single port and a single endpoint, or two ports and two endpoints. I > think dual link has to be single port & endpoint, as the TMDS links need > to be driven together as a single bus. > > And dual-link is not really "two links". DVI dual-link means 1 clock > lane and 6 data lanes, compared to 1 clock lane and 3 data lanes for > single-link. What about having a property for the number of data lanes? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ``` ## Re: \[PATCH 3/9\] Doc/DT: Add DT binding documentation for DVI Connector - From: Tomi Valkeinen \ - Date: 2014-03-11 08:04:21 - Message: https://ratatoskr.run/linux-fbdev/2014/03/8087118.md ```text On 11/03/14 10:00, Geert Uytterhoeven wrote: > On Tue, Mar 11, 2014 at 7:39 AM, Tomi Valkeinen [ref] wrote: >> On 10/03/14 23:45, Rob Herring wrote: >>> I like this proposal over the others. Although, would dual link be a >> >> I don't like inferring the information. With the above, you can't find >> out that the DVI connector has digital and analog support before all the >> drivers are loaded. >> >>> single endpoint or 2 endpoints? How would you differentiate that? >> >> Hmm, well endpoints for a single port are exclusive. So it's either a >> single port and a single endpoint, or two ports and two endpoints. I >> think dual link has to be single port & endpoint, as the TMDS links need >> to be driven together as a single bus. >> >> And dual-link is not really "two links". DVI dual-link means 1 clock >> lane and 6 data lanes, compared to 1 clock lane and 3 data lanes for >> single-link. > > What about having a property for the number of data lanes? That was already suggested by Philipp in this thread. I don't see anything wrong with that, but I don't really see benefit either. "dual-link" is a standard term for 6 data lanes for the DVI connector. And the choices are 3 or 6 data lanes, nothing else. Tomi ``` ## Re: \[PATCH 3/9\] Doc/DT: Add DT binding documentation for DVI Connector - From: Philipp Zabel \ - Date: 2014-03-11 11:19:00 - Message: https://ratatoskr.run/linux-fbdev/2014/03/8087132.md ```text Am Dienstag, den 11.03.2014, 10:04 +0200 schrieb Tomi Valkeinen: > On 11/03/14 10:00, Geert Uytterhoeven wrote: > > On Tue, Mar 11, 2014 at 7:39 AM, Tomi Valkeinen [ref] wrote: > >> On 10/03/14 23:45, Rob Herring wrote: > >>> I like this proposal over the others. Although, would dual link be a > >> > >> I don't like inferring the information. With the above, you can't find > >> out that the DVI connector has digital and analog support before all the > >> drivers are loaded. > >> > >>> single endpoint or 2 endpoints? How would you differentiate that? > >> > >> Hmm, well endpoints for a single port are exclusive. So it's either a > >> single port and a single endpoint, or two ports and two endpoints. I > >> think dual link has to be single port & endpoint, as the TMDS links need > >> to be driven together as a single bus. > >> > >> And dual-link is not really "two links". DVI dual-link means 1 clock > >> lane and 6 data lanes, compared to 1 clock lane and 3 data lanes for > >> single-link. > > > > What about having a property for the number of data lanes? > > That was already suggested by Philipp in this thread. I don't see > anything wrong with that, but I don't really see benefit either. > "dual-link" is a standard term for 6 data lanes for the DVI connector. > And the choices are 3 or 6 data lanes, nothing else. The number of lanes of a DisplayPort connector could be 1 to 4. Also, there's dual-mode DP which can use four lanes to drive somewhat-like-HDMI single link TMDS signals. regards Philipp ```