Hi Rob,
Thank you for the patch.
On Sun, Jun 30, 2019 at 01:36:04PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> Now that we can deal gracefully with bootloader (firmware) initialized
> display on aarch64 laptops[1], the next step is to deal with the fact
> that the same model of laptop can have one of multiple different panels.
> (For the yoga c630 that I have, I know of at least two possible panels,
> there might be a third.)
I have to ask the obvious question: why doesn't the boot loader just
pass a correct DT to Linux ? There's no point in passing a list of
panels that are not there, this seems quite a big hack to me. A proper
boot loader should construct the DT based on hardware detection.
> This is actually a scenario that comes up frequently in phones and
> tablets as well, so it is useful to have an upstream solution for this.
>
> The basic idea is to add a 'panel-id' property in dt chosen node, and
> use that to pick the endpoint we look at when loading the panel driver,
> e.g.
>
> / {
> chosen {
> panel-id = <0xc4>;
> };
>
> ivo_panel {
> compatible = "ivo,m133nwf4-r0";
> power-supply = <&vlcm_3v3>;
> no-hpd;
>
> ports {
> port {
> ivo_panel_in_edp: endpoint {
> remote-endpoint = <&sn65dsi86_out_ivo>;
> };
> };
> };
> };
>
> boe_panel {
> compatible = "boe,nv133fhm-n61";
> power-supply = <&vlcm_3v3>;
> no-hpd;
>
> ports {
> port {
> boe_panel_in_edp: endpoint {
> remote-endpoint = <&sn65dsi86_out_boe>;
> };
> };
> };
> };
>
> sn65dsi86: bridge@2c {
> compatible = "ti,sn65dsi86";
>
> ...
>
> ports {
> #address-cells = <1>;
> #size-cells = <0>;
>
> ...
>
> port@1 {
> #address-cells = <1>;
> #size-cells = <0>;
> reg = <1>;
>
> endpoint@c4 {
> reg = <0xc4>;
> remote-endpoint = <&boe_panel_in_edp>;
> };
>
> endpoint@c5 {
> reg = <0xc5>;
> remote-endpoint = <&ivo_panel_in_edp>;
> };
> };
> };
> }
> };
>
> Note that the panel-id is potentially a sparse-int. The values I've
> seen so far on aarch64 laptops are:
>
> * 0xc2
> * 0xc3
> * 0xc4
> * 0xc5
> * 0x8011
> * 0x8012
> * 0x8055
> * 0x8056
>
> At least on snapdragon aarch64 laptops, they can be any u32 value.
>
> However, on these laptops, the bootloader/firmware is not populating the
> chosen node, but instead providing an "UEFIDisplayInfo" variable, which
> contains the panel id. Unfortunately EFI variables are only available
> before ExitBootServices, so the second patch checks for this variable
> before EBS and populates the /chosen/panel-id variable.
>
> [1] https://patchwork.freedesktop.org/series/63001/
>
> Rob Clark (4):
> dt-bindings: chosen: document panel-id binding
> efi/libstub: detect panel-id
> drm: add helper to lookup panel-id
> drm/bridge: ti-sn65dsi86: use helper to lookup panel-id
>
> Documentation/devicetree/bindings/chosen.txt | 69 ++++++++++++++++++++
> drivers/firmware/efi/libstub/arm-stub.c | 49 ++++++++++++++
> drivers/firmware/efi/libstub/efistub.h | 2 +
> drivers/firmware/efi/libstub/fdt.c | 9 +++
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 5 +-
> drivers/gpu/drm/drm_of.c | 21 ++++++
> include/drm/drm_of.h | 7 ++
> 7 files changed, 160 insertions(+), 2 deletions(-)
--
Regards,
Laurent Pinchart
