connecting a sn65dsi86 to displayport connector

[Doug Anderson]

Hi,

On Tue, Jul 5, 2022 at 8:10 AM Kieran Bingham
<kieran.bingham+renesas at ideasonboard.com> wrote:
>
> Hi Rasmus,
>
> Quoting Rasmus Villemoes (2022-07-05 10:08:37)
> > Hi
> >
> > I have an imx8mp board with a sn65dsi86 and a (full-size) DisplayPort
> > connector, which I'm trying to get up and running.
> >
> > The display connector registers itself as a bridge; I do get
> > successfully to the end of display_connector_probe(). But
> > ti_sn_bridge_probe() only looks for a panel (passing NULL for the
> > drm_bridge** argument), so always fails with -EPROBE_DEFER.
> >
> > This text
> >
> >   At the moment, this binding only handles the eDP case. It is
> >   possible it will be extended in the future to handle the DP case.
> >   For DP, presumably a connector would be listed under the DP AUX
> >   bus instead of a panel.
> >
> > in dp-aux-bus.yaml suggests that what I'm trying to do is simply not
> > supported yet. But then I stumbled on commit 5a6bca1ff7a5 (arm64: dts:
> > renesas: falcon-cpu: Add DSI display output), which seems to do exactly
> > what I'm trying to, except with a mini dp connector. So I must be
> > missing something; maybe ti_sn_bridge_probe() failing is not actually a
> > problem and I could be looking at the wrong place.
> >
> > Snippets from my .dts; the dp connector is currently placed at top
> > level, i.e. not within an aux-bus node below the sn65dsi86:
> >
> >         display_port0: connector {
> >                 compatible = "dp-connector";
> >                 label = "DP0";
> >                 type = "full-size";
> >                 dp-pwr-supply = <&reg_DP_PWR>;
> >
> >                 port {
> >                         dp_connector_in: endpoint {
> >                                 remote-endpoint = <&sn65dsi86_out>;
> >                         };
> >                 };
> >         };
> >
> > &i2c5 {
> > ...
> >         eDP: bridge at 2c {
> >                 compatible = "ti,sn65dsi86";
> >                 reg = <0x2c>;
> >                 pinctrl-names = "default";
> >                 pinctrl-0 = <&pinctrl_eDP>;
> >
> >                 interrupts-extended = <&gpio3 14 IRQ_TYPE_LEVEL_HIGH>;
> >                 enable-gpios = <&gpio3 9 GPIO_ACTIVE_HIGH>;
> >
> >                 vpll-supply = <&VDD_1V8>;
> >                 vccio-supply = <&VDD_1V8>;
> >                 vcca-supply = <&reg_1V2>;
> >                 vcc-supply = <&reg_1V2>;
> >
> >                 clocks = <&clk_38_4MHz>;
> >                 clock-names = "refclk";
> >
> >                 ports {
> >                         #address-cells = <1>;
> >                         #size-cells = <0>;
> >
> >                         port at 0 {
> >                                 reg = <0>;
> >                                 sn65dsi86_in_a: endpoint {
> >                                         remote-endpoint = <&mipi_dsi_out>;
> >                                 };
> >                         };
> >
> >                         port at 1 {
> >                                 reg = <1>;
> >                                 sn65dsi86_out: endpoint {
> >                                         remote-endpoint = <&dp_connector_in>;
> >                                         data-lanes = <3 2 1 0>;
> >                                 };
> >                         };
> >                 };
> >         };
> > };
> >
> > When I manually set the enable-gpio high in U-Boot, I can talk to the
> > device and e.g. read out the 8 device_id bytes which match what I expect.
> >
> > Any hints would be highly appreciated.
>
> If it helps, this is an area I've been working to support one of our
> boards. I have a branch at:
>
>  git://git.kernel.org/pub/scm/linux/kernel/git/kbingham/rcar.git
>  kbingham/drm-misc/next/sn65dsi86/hpd
>
> But it's still a work in progress, and now needs rebasing to account for
> Sam's latest updates.
>
> I intend to resume this in a few weeks, but hopefully that branch may
> have some helpful pointers to get things progressing for you too.

In case you didn't notice, Dmitry's latest series is probably
interesting to you.

https://lore.kernel.org/r/20220711092117.360797-1-dmitry.baryshkov@linaro.org/


-Doug