drm/bridge: parade-ps8640: Populate devices on aux-bus

Conventionally, panel is listed under the root of the device tree.
When userland asks for display mode, ps8640 bridge is responsible
for returning EDID when ps8640_bridge_get_edid() is called.

Now enable a new option of listing panel under "aux-bus" of ps8640
bridge node in the device tree. In this case, panel driver can retrieve
EDID by triggering AUX transactions, without ps8640_bridge_get_edid()
calls at all.

To prevent the "old" and "new" options from interfering with each
other's logic flow, disable DRM_BRIDGE_OP_EDID when the new option
is taken.

Signed-off-by: Philip Chen <philipchen@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211028105754.v5.2.I09899dea340f11feab97d719cb4b62bef3179e4b@changeid

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 431b6e1..61db5a6 100644 (file)
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -182,6 +182,7 @@ config DRM_PARADE_PS8622
 config DRM_PARADE_PS8640
        tristate "Parade PS8640 MIPI DSI to eDP Converter"
        depends on OF
+       select DRM_DP_AUX_BUS
        select DRM_KMS_HELPER
        select DRM_MIPI_DSI
        select DRM_PANEL

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
index 7d797cf..345bb2b 100644 (file)
--- a/drivers/gpu/drm/bridge/parade-ps8640.c
+++ b/drivers/gpu/drm/bridge/parade-ps8640.c
@@ -14,6 +14,7 @@
 #include <linux/regulator/consumer.h>
 
 #include <drm/drm_bridge.h>
+#include <drm/drm_dp_aux_bus.h>
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_of.h>
@@ -149,6 +150,23 @@ static inline struct ps8640 *aux_to_ps8640(struct drm_dp_aux *aux)
        return container_of(aux, struct ps8640, aux);
 }
 
+static bool ps8640_of_panel_on_aux_bus(struct device *dev)
+{
+       struct device_node *bus, *panel;
+
+       bus = of_get_child_by_name(dev->of_node, "aux-bus");
+       if (!bus)
+               return false;
+
+       panel = of_get_child_by_name(bus, "panel");
+       of_node_put(bus);
+       if (!panel)
+               return false;
+       of_node_put(panel);
+
+       return true;
+}
+
 static int ps8640_ensure_hpd(struct ps8640 *ps_bridge)
 {
        struct regmap *map = ps_bridge->regmap[PAGE2_TOP_CNTL];
@@ -555,17 +573,6 @@ static int ps8640_probe(struct i2c_client *client)
        if (!ps_bridge)
                return -ENOMEM;
 
-       /* port@1 is ps8640 output port */
-       ret = drm_of_find_panel_or_bridge(np, 1, 0, &panel, NULL);
-       if (ret < 0)
-               return ret;
-       if (!panel)
-               return -ENODEV;
-
-       ps_bridge->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
-       if (IS_ERR(ps_bridge->panel_bridge))
-               return PTR_ERR(ps_bridge->panel_bridge);
-
        ps_bridge->supplies[0].supply = "vdd33";
        ps_bridge->supplies[1].supply = "vdd12";
        ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ps_bridge->supplies),
@@ -588,9 +595,16 @@ static int ps8640_probe(struct i2c_client *client)
 
        ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
        ps_bridge->bridge.of_node = dev->of_node;
-       ps_bridge->bridge.ops = DRM_BRIDGE_OP_EDID;
        ps_bridge->bridge.type = DRM_MODE_CONNECTOR_eDP;
 
+       /*
+        * In the device tree, if panel is listed under aux-bus of the bridge
+        * node, panel driver should be able to retrieve EDID by itself using
+        * aux-bus. So let's not set DRM_BRIDGE_OP_EDID here.
+        */
+       if (!ps8640_of_panel_on_aux_bus(&client->dev))
+               ps_bridge->bridge.ops = DRM_BRIDGE_OP_EDID;
+
        ps_bridge->page[PAGE0_DP_CNTL] = client;
 
        ps_bridge->regmap[PAGE0_DP_CNTL] = devm_regmap_init_i2c(client, ps8640_regmap_config);
@@ -633,6 +647,19 @@ static int ps8640_probe(struct i2c_client *client)
        if (ret)
                return ret;
 
+       devm_of_dp_aux_populate_ep_devices(&ps_bridge->aux);
+
+       /* port@1 is ps8640 output port */
+       ret = drm_of_find_panel_or_bridge(np, 1, 0, &panel, NULL);
+       if (ret < 0)
+               return ret;
+       if (!panel)
+               return -ENODEV;
+
+       ps_bridge->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
+       if (IS_ERR(ps_bridge->panel_bridge))
+               return PTR_ERR(ps_bridge->panel_bridge);
+
        drm_bridge_add(&ps_bridge->bridge);
 
        ret = ps8640_bridge_host_attach(dev, ps_bridge);