panel-edp.yaml

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    1 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
    2 %YAML 1.2
    3 ---
    4 $id: http://devicetree.org/schemas/display/panel/panel-edp.yaml#
    5 $schema: http://devicetree.org/meta-schemas/core.yaml#
    6 
    7 title: Probeable (via DP AUX / EDID) eDP Panels with simple poweron sequences
    8 
    9 maintainers:
   10   - Douglas Anderson <dianders@chromium.org>
   11 
   12 description: |
   13   This binding file can be used to indicate that an eDP panel is connected
   14   to a Embedded DisplayPort AUX bus (see display/dp-aux-bus.yaml) without
   15   actually specifying exactly what panel is connected. This is useful for
   16   the case that more than one different panel could be connected to the
   17   board, either for second-sourcing purposes or to support multiple SKUs
   18   with different LCDs that hook up to a common board.
   19 
   20   As per above, a requirement for using this binding is that the panel is
   21   represented under the DP AUX bus. This means that we can use any
   22   information provided by the DP AUX bus (including the EDID) to identify
   23   the panel. We can use this to identify display size, resolution, and
   24   timings among other things.
   25 
   26   One piece of information about eDP panels that is typically _not_
   27   provided anywhere on the DP AUX bus is the power sequencing timings.
   28   This is the reason why, historically, we've always had to explicitly
   29   list eDP panels. We solve that here with two tricks. The "worst case"
   30   power on timings for any panels expected to be connected to a board are
   31   specified in these bindings. Once we've powered on, it's expected that
   32   the operating system will lookup the panel in a table (based on EDID
   33   information) to figure out other power sequencing timings.
   34 
   35   eDP panels in general can have somewhat arbitrary power sequencing
   36   requirements. However, even though it's arbitrary in general, the
   37   vast majority of panel datasheets have a power sequence diagram that
   38   looks the exactly the same as every other panel. Each panel datasheet
   39   cares about different timings in this diagram but the fact that the
   40   diagram is so similar means we can come up with a single driver to
   41   handle it.
   42 
   43   These diagrams all look roughly like this, sometimes labeled with
   44   slightly different numbers / lines but all pretty much the same
   45   sequence. This is because much of this diagram comes straight from
   46   the eDP Standard.
   47 
   48                 __________________________________________________
   49   Vdd       ___/:                                                :\____       /
   50           _/    :                                                :     \_____/
   51            :<T1>:<T2>:                                 :<--T10-->:<T11>:<T12>:
   52                 :    +-----------------------+---------+---------+
   53   eDP     -----------+ Black video           | Src vid | Blk vid +
   54   Display       :    +-----------------------+---------+---------+
   55                 :     _______________________:_________:_________:
   56   HPD           :<T3>|                       :         :         |
   57           ___________|                       :         :         |_____________
   58                      :                       :         :         :
   59   Sink               +-----------------------:---------:---------+
   60   AUX CH  -----------+ AUX Ch operational    :         :         +-------------
   61                      +-----------------------:---------:---------+
   62                      :                       :         :         :
   63                      :<T4>:             :<T7>:         :         :
   64   Src main                +------+------+--------------+---------+
   65   lnk data----------------+LnkTrn| Idle |Valid vid data| Idle/off+-------------
   66                           +------+------+--------------+---------+
   67                           : <T5> :<-T6->:<-T8->:       :
   68                                                :__:<T9>:
   69   LED_EN                                       |  |
   70           _____________________________________|  |____________________________
   71                                                :  :
   72                                      __________:__:_
   73   PWM                               |          :  : |
   74           __________________________|          :  : |__________________________
   75                                     :          :  : :
   76                        _____________:__________:__:_:______
   77   Bklight         ____/:            :          :  : :     :\____
   78   power   _______/     :<---T13---->:          :  : :<T16>:     \______________
   79   (Vbl)          :<T17>:<---------T14--------->:  :<-T15->:<T18>:
   80 
   81   The above looks fairly complex but, as per above, each panel only cares
   82   about a subset of those timings.
   83 
   84 allOf:
   85   - $ref: panel-common.yaml#
   86 
   87 properties:
   88   compatible:
   89     const: edp-panel
   90 
   91   hpd-reliable-delay-ms:
   92     description:
   93       A fixed amount of time that must be waited after powering on the
   94       panel's power-supply before the HPD signal is a reliable way to know
   95       when the AUX channel is ready. This is useful for panels that glitch
   96       the HPD at the start of power-on. This value is not needed if HPD is
   97       always reliable for all panels that might be connected.
   98 
   99   hpd-absent-delay-ms:
  100     description:
  101       The panel specifies that HPD will be asserted this many milliseconds
  102       from power on (timing T3 in the diagram above). If we have no way to
  103       measure HPD then a fixed delay of this many milliseconds can be used.
  104       This can also be used as a timeout when waiting for HPD. Does not
  105       include the hpd-reliable-delay, so if hpd-reliable-delay was 80 ms
  106       and hpd-absent-delay was 200 ms then we'd do a fixed 80 ms delay and
  107       then we know HPD would assert in the next 120 ms. This value is not
  108       needed if HPD hooked up, either through a GPIO in the panel node or
  109       hooked up directly to the eDP controller.
  110 
  111   backlight: true
  112   enable-gpios: true
  113   port: true
  114   power-supply: true
  115   no-hpd: true
  116   hpd-gpios: true
  117 
  118 additionalProperties: false
  119 
  120 required:
  121   - compatible
  122   - power-supply
  123 
  124 examples:
  125   - |
  126     #include <dt-bindings/clock/qcom,rpmh.h>
  127     #include <dt-bindings/gpio/gpio.h>
  128     #include <dt-bindings/interrupt-controller/irq.h>
  129 
  130     i2c {
  131       #address-cells = <1>;
  132       #size-cells = <0>;
  133 
  134       bridge@2d {
  135         compatible = "ti,sn65dsi86";
  136         reg = <0x2d>;
  137 
  138         interrupt-parent = <&tlmm>;
  139         interrupts = <10 IRQ_TYPE_LEVEL_HIGH>;
  140 
  141         enable-gpios = <&tlmm 102 GPIO_ACTIVE_HIGH>;
  142 
  143         vpll-supply = <&src_pp1800_s4a>;
  144         vccio-supply = <&src_pp1800_s4a>;
  145         vcca-supply = <&src_pp1200_l2a>;
  146         vcc-supply = <&src_pp1200_l2a>;
  147 
  148         clocks = <&rpmhcc RPMH_LN_BB_CLK2>;
  149         clock-names = "refclk";
  150 
  151         no-hpd;
  152 
  153         ports {
  154           #address-cells = <1>;
  155           #size-cells = <0>;
  156 
  157           port@0 {
  158             reg = <0>;
  159             endpoint {
  160               remote-endpoint = <&dsi0_out>;
  161             };
  162           };
  163 
  164           port@1 {
  165             reg = <1>;
  166             sn65dsi86_out: endpoint {
  167               remote-endpoint = <&panel_in_edp>;
  168             };
  169           };
  170         };
  171 
  172         aux-bus {
  173           panel {
  174             compatible = "edp-panel";
  175             power-supply = <&pp3300_dx_edp>;
  176             backlight = <&backlight>;
  177             hpd-gpios = <&sn65dsi86_bridge 2 GPIO_ACTIVE_HIGH>;
  178             hpd-reliable-delay-ms = <15>;
  179 
  180             port {
  181               panel_in_edp: endpoint {
  182                 remote-endpoint = <&sn65dsi86_out>;
  183               };
  184             };
  185           };
  186         };
  187       };
  188     };

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FreeBSD/Linux Kernel Cross Reference sys/contrib/device-tree/Bindings/display/panel/panel-edp.yaml

FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/display/panel/panel-edp.yaml