Other Parts Discussed in Thread: TPD12S015, , DRA742
Tool/software: Linux
I have an custom AM5728 board that works under the v3.00 PSDK but the HDMI system failing when I try to update the system to use the 04.01 PSDK. The board is based on a Compulab AM5728 SOM on top of my own custom carrier board and does NOT have a TPD12S015 HDMI level shifter as the AM5728-EVM/Beagle-X15 systems do. The board only uses HDMI. As the format of the TI dts/dtsi system for the am57xx-evm has expanded since the v3.00 release I am atempting to update my dts to the new linux kerenel system using the evm as a starting point. Where I'm running into problems is that my HDMI is not being configured correctly. and I'm getting many "connector-hdmi connector: failed to find video source" lines emitted into the console log on boot.
My original Version 3.0 Device tree include map looks like the following:
am57xx-aii-compulab.dts
dt-bindings/input/input.h
am57xx-cl-som-am57x.dtsi*
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/interrupt-controller/irq.h>
#include "dra74x.dtsi"
#include "dra7.dtsi"
#include <dt-bindings/interrupt-controller/arm-gic.h>
#include <dt-bindings/pinctrl/dra.h>
#include "skeleton.dtsi"
#include <dt-bindings/clk/ti-dra7-atl.h>
*am57xx-cl-som-am57x.dtsi doesn't have definitions related to HDMI/DRM
and the related code in am57xx-aii-compulab.dts that configures the hdmi looks like the following:
/ {
model = "Assurance 5728 Weld Controller";
compatible = "aii,assurance5728", "compulab,cl-som-am57x", "ti,am5728", "ti,dra742", "ti,dra74", "ti,dra7";
aliases {
display0 = &hdmi;
};
hdmi_conn: connector@0 {
compatible = "hdmi-connector";
label = "hdmi";
type = "a";
};
};
&dra7_pmx_core {
hdmi_pins: pinmux_hdmi_pins {
pinctrl-single,pins = <
DRA7XX_CORE_IOPAD(0x3808, PIN_INPUT | MUX_MODE1) /* i2c2_sda.hdmi1_ddc_scl */
DRA7XX_CORE_IOPAD(0x380c, PIN_INPUT | MUX_MODE1) /* i2c2_scl.hdmi1_ddc_sda */
>;
};
hdmi_conn_pins: pinmux_hdmi_conn_pins {
pinctrl-single,pins = <
DRA7XX_CORE_IOPAD(0x37b8, PIN_INPUT | MUX_MODE14) /* spi1_cs2.gpio7_12 */
>;
};
};
&hdmi {
status = "ok";
vdda-supply = <&ldo4_reg>;
pinctrl-names = "default";
pinctrl-0 = <&hdmi_pins>;
port {
hdmi_out: endpoint {
remote-endpoint = <&hdmi_connector_in>;
lanes = <1 0 3 2 5 4 7 6>;
};
};
};
&hdmi_conn {
pinctrl-names = "default";
pinctrl-0 = <&hdmi_conn_pins>;
hpd-gpios = <&gpio7 12 GPIO_ACTIVE_HIGH>;
port {
hdmi_connector_in: endpoint {
remote-endpoint = <&hdmi_out>;
};
};
};
Now on the AM57xx-evm, the HDMI system is apparently coupled through a tpd12s015 level converter and so all the device tree bits configure that in place of the more generic "hdmi-connector" that is used om my machine. The tpd12s015 is pretty much a pass-through device/level shifter but it needs 2 extra enables (CT_CP_HPD and LS_OE) which as not present in my case.
I looked at just faking the tpd12s015 device and aiming the two "extra" GPIO at unused pins but don't really want to dedicate 2 pins if i can help it. I looked somewhat briefly at the lower level dts files (dra74 and dra7) and didn't see anything that changed down there between v3.00 and v4.01.
Obviously I'm not configuring something correctly to account for changes since v3.00 - so some questions:
1. I'm looking at the drivers and it's unclear how the video source gets routed from the dss to the the HDMI. Can someone provide a quick explanation of how this is supposed to be "wired up" in the device tree.
i.e. explain the relationships between dss, encoders, connectors or point me to the documentation.
2. Given that the TI device trees all seem to use the tpd12s015 driver(s) (there are two!)- is it possible that there is now a bug in the more generic "hdmi-connector" driver that has gone unnoticed?
3. is there any debugging I can turn on to help track down what could be going wrong with this config.
