| Message ID | 1428920545.3192.41.camel@pengutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Thanks Philipp, On 04/13/2015 03:22 AM, Philipp Zabel wrote: > Hi Eric, > > Am Sonntag, den 05.04.2015, 18:25 -0700 schrieb Eric Nelson: >> Hi Philipp, >> >> Sorry for the delayed response. I missed your reply and Shawn pointed >> it out. > [...] >> The use of simple panel seems to add and remove functionality: >> - adds backlight, regulators and enable GPIOs! >> - loses the ability to express timings in DT > > For the simple panel driver Thierry preferred to have a panel database > in the driver and uniquely identify the panel by its compatible value. > This will also allow to infer the data mapping and width from > the panel, and the panel timings are available for the next hardware to > reuse the same panel (however likely that is). > > The old method with display-timings will stay available, but for > mainline I think it is better to add the panel to the driver. > I predict that panel-simple.c will get really big, really fast. Scanning it for panels that match our Okaya 1024x600 panel shows that there already four with that resolution which seem to differ only in margin timings. I think the addition of an optional display-timings node and/or a VESA GTF mode string would prevent a lot of churn, but this is a separate topic. >>> After: >>> ldb { >>> ... >>> >>> lvds-channel at 0 { >>> ... >>> >> >> Using port here to point at the panel seems to conflict >> with the use of ports to point at the IPU. > > I'm sorry, I don't understand what you mean exactly. There are some > input ports (two on i.MX5, four on i.MX6) that are connected to the IPU, > and one output port that is connected to the panel, in that order by > convention. The port id 4 (reg = <4>) uniquely identifies the output > port on i.MX6. > The full DT for an LVDS channel looks like this: ... lvds-channel@0 { #address-cells = <0x00000001>; #size-cells = <0x00000000>; ... port@0 { reg = <0x00000000>; endpoint { remote-endpoint = <0x00000013>; linux,phandle = <0x00000039>; phandle = <0x00000039>; }; }; port@1 { ... }; port@2 { ... }; port@3 { ... }; port@4 { reg = <0x00000004>; endpoint { remote-endpoint = <0x00000017>; linux,phandle = <0x00000053>; phandle = <0x00000053>; }; }; }; ports 0-3 refer to the LVDS mux and which IPU and display interface is connected up to the LVDS channel (i.e. the input to the LVDS display bridge) and port@4 refer to the panel. >>> [snip] >>> >>> panel { >>> compatible = "edt,etm0700g0dh6", "simple-panel"; >>> ... >>> >> >> And why would the panel need to point back to the LVDS >> channel? > > This is the way the bindings are defined right now in > Documentation/devicetree/bindings/graph.txt, section "Links between > endpoints". The panel driver itself doesn't use the backlink, but the > endpoint needs to exist anyway. > Thanks for the reference. I'm not following the rationale since in this case, the communication needs seem to be uni-directional, but okay. >> [snip] >> >> Do you have a working example of how this should be used? >> >> My attempts to follow the notes above results in a failure >> to find a crtc for the LVDS channel. >> >> Please advise, > > I have used this patch to connect a HannStar HSD070PWW1 LVDS panel to a > Nitrogen6X board: > Thanks again. This patch works for me with your prior patch applied: https://patchwork.kernel.org/patch/5854771/ > -----8<----- > diff --git a/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi b/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi > index 0821812..9e52adf 100644 > --- a/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi > +++ b/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi > @@ -122,7 +122,7 @@ > status = "okay"; > }; > > - backlight_lvds { > + backlight_lvds: backlight_lvds { > compatible = "pwm-backlight"; > pwms = <&pwm4 0 5000000>; > brightness-levels = <0 4 8 16 32 64 128 255>; > @@ -130,6 +130,17 @@ > power-supply = <®_3p3v>; > status = "okay"; > }; > + > + panel { > + compatible = "hannstar,hsd070pww1"; > + backlight = <&backlight_lvds>; > + > + port { > + panel_in: endpoint { > + remote-endpoint = <&lvds0_out>; > + }; > + }; > + }; > }; > This does give me a path to get the equivalent functionality as my original patches: - (if needed) add displays to panel-simple.c - update DT in boot loader to fix up displays based on panel detection by setting the panel.compatible string value. I am still left with a quandary, which relates to my comment about the port selection. With our current device tree, both the HDMI and LVDS devices are being mapped to IPU1/DI0 and the same DRM "card": ~# ls /sys/class/graphics/fb0/device/drm/card0/card* card0-HDMI-A-1 card0-LVDS-1 Since the default i.MX6 graph appears to have links for all four LVDS mux options, and the path to binding to one of the IPU/DI -> LVDS channel mappings isn't clear to me. I have the same question for HDMI and LCD interfaces though, and this is a separate topic. Regards, Eric
Hi Eric, Am Montag, den 13.04.2015, 12:48 -0700 schrieb Eric Nelson: [...] > The full DT for an LVDS channel looks like this: > > ... > lvds-channel@0 { > #address-cells = <0x00000001>; > #size-cells = <0x00000000>; > ... > port@0 { > reg = <0x00000000>; > endpoint { > remote-endpoint = <0x00000013>; > linux,phandle = <0x00000039>; > phandle = <0x00000039>; > }; > }; > port@1 { > ... }; > port@2 { > ... }; > port@3 { > ... }; > port@4 { > reg = <0x00000004>; > endpoint { > remote-endpoint = <0x00000017>; > linux,phandle = <0x00000053>; > phandle = <0x00000053>; > }; > }; > }; > > ports 0-3 refer to the LVDS mux and which IPU and display > interface is connected up to the LVDS channel (i.e. the > input to the LVDS display bridge) and port@4 refer to the > panel. Yes. I still don't understand what you think is the problem with that. > >>> [snip] > >>> > >>> panel { > >>> compatible = "edt,etm0700g0dh6", "simple-panel"; > >>> ... > >>> > >> > >> And why would the panel need to point back to the LVDS > >> channel? > > > > This is the way the bindings are defined right now in > > Documentation/devicetree/bindings/graph.txt, section "Links between > > endpoints". The panel driver itself doesn't use the backlink, but the > > endpoint needs to exist anyway. > > > > Thanks for the reference. > > I'm not following the rationale since in this case, the communication > needs seem to be uni-directional, but okay. The binding as currently defined describes an undirected graph, set up in a way that each node can find its peers without knowing anything about the peer's bindings and without scanning the whole device tree. So far there has been no consensus whether a direction should be added, if it should be marked by leaving out one of the phandles, and if so, what this direction should represent. [...] > This does give me a path to get the equivalent functionality > as my original patches: > > - (if needed) add displays to panel-simple.c > - update DT in boot loader to fix up displays based on panel > detection by setting the panel.compatible string value. > > I am still left with a quandary, which relates to my comment about > the port selection. > > With our current device tree, both the HDMI and LVDS devices > are being mapped to IPU1/DI0 and the same DRM "card": > > ~# ls /sys/class/graphics/fb0/device/drm/card0/card* > card0-HDMI-A-1 card0-LVDS-1 There is only one "card" representing both IPUs and everything connected to their DI outputs. Both connectors being mapped to the same frame buffer is a property of drm_fb_helper_initial_config, as described in its kerneldoc comment: "At the moment, this is a cloned configuration across all heads with a new framebuffer object as the backing store." > Since the default i.MX6 graph appears to have links for all four LVDS > mux options, and the path to binding to one of the IPU/DI -> LVDS > channel mappings isn't clear to me. All four LVDS mux options are connected in hardware, so that's what the device tree describes. The path can be chosen dynamically via CRTC modeset. regards Philipp
diff --git a/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi b/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi index 0821812..9e52adf 100644 --- a/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi +++ b/arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi @@ -122,7 +122,7 @@ status = "okay"; }; - backlight_lvds { + backlight_lvds: backlight_lvds { compatible = "pwm-backlight"; pwms = <&pwm4 0 5000000>; brightness-levels = <0 4 8 16 32 64 128 255>; @@ -130,6 +130,17 @@ power-supply = <®_3p3v>; status = "okay"; }; + + panel { + compatible = "hannstar,hsd070pww1"; + backlight = <&backlight_lvds>; + + port { + panel_in: endpoint { + remote-endpoint = <&lvds0_out>; + }; + }; + }; }; &audmux { @@ -379,18 +390,11 @@ fsl,data-width = <18>; status = "okay"; - display-timings { - native-mode = <&timing0>; - timing0: hsd100pxn1 { - clock-frequency = <65000000>; - hactive = <1024>; - vactive = <768>; - hback-porch = <220>; - hfront-porch = <40>; - vback-porch = <21>; - vfront-porch = <7>; - hsync-len = <60>; - vsync-len = <10>; + port@4 { + reg = <4>; + + lvds0_out: endpoint { + remote-endpoint = <&panel_in>; }; }; };