drm/tegra: Implement panel support

Use the DRM panel framework to attach a panel to an output. If the panel
attached to a connector supports supports the backlight brightness
accessors, a property will be available to allow the brightness to be
modified from userspace.

Signed-off-by: Thierry Reding <treding@nvidia.com>

4 files changed, 38 insertions, 4 deletions

diff --git a/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt b/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt
index ab45c02aa658..31314bd40da9 100644
--- a/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt
+++ b/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt
@@ -125,6 +125,7 @@ of the following host1x client modules:
   - nvidia,ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
   - nvidia,hpd-gpio: specifies a GPIO used for hotplug detection
   - nvidia,edid: supplies a binary EDID blob
+  - nvidia,panel: phandle of a display panel
 
 - hdmi: High Definition Multimedia Interface
 
@@ -149,6 +150,7 @@ of the following host1x client modules:
   - nvidia,ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
   - nvidia,hpd-gpio: specifies a GPIO used for hotplug detection
   - nvidia,edid: supplies a binary EDID blob
+  - nvidia,panel: phandle of a display panel
 
 - tvo: TV encoder output
 
diff --git a/drivers/gpu/drm/tegra/Kconfig b/drivers/gpu/drm/tegra/Kconfig
index 8db9b3bce001..1b5448cd6829 100644
--- a/drivers/gpu/drm/tegra/Kconfig
+++ b/drivers/gpu/drm/tegra/Kconfig
@@ -6,6 +6,7 @@ config DRM_TEGRA
         select TEGRA_HOST1X
         select DRM_KMS_HELPER
         select DRM_KMS_FB_HELPER
+        select DRM_PANEL
         select FB_SYS_FILLRECT
         select FB_SYS_COPYAREA
         select FB_SYS_IMAGEBLIT
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 266aae08a3bd..bb8b1305606e 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -186,6 +186,7 @@ struct tegra_output {
         const struct tegra_output_ops *ops;
         enum tegra_output_type type;
 
+        struct drm_panel *panel;
         struct i2c_adapter *ddc;
         const struct edid *edid;
         unsigned int hpd_irq;
diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c
index 2cb0065e0578..5dc4d1a9cad8 100644
--- a/drivers/gpu/drm/tegra/output.c
+++ b/drivers/gpu/drm/tegra/output.c
@@ -9,6 +9,7 @@
 
 #include <linux/of_gpio.h>
 
+#include <drm/drm_panel.h>
 #include "drm.h"
 
 static int tegra_connector_get_modes(struct drm_connector *connector)
@@ -17,6 +18,12 @@ static int tegra_connector_get_modes(struct drm_connector *connector)
         struct edid *edid = NULL;
         int err = 0;
 
+        if (output->panel) {
+                err = output->panel->funcs->get_modes(output->panel);
+                if (err > 0)
+                        return err;
+        }
+
         if (output->edid)
                 edid = kmemdup(output->edid, sizeof(*edid), GFP_KERNEL);
         else if (output->ddc)
@@ -72,6 +79,11 @@ tegra_connector_detect(struct drm_connector *connector, bool force)
                 else
                         status = connector_status_connected;
         } else {
+                if (!output->panel)
+                        status = connector_status_disconnected;
+                else
+                        status = connector_status_connected;
+
                 if (connector->connector_type == DRM_MODE_CONNECTOR_LVDS)
                         status = connector_status_connected;
         }
@@ -115,6 +127,15 @@ static const struct drm_encoder_funcs encoder_funcs = {
 
 static void tegra_encoder_dpms(struct drm_encoder *encoder, int mode)
 {
+        struct tegra_output *output = encoder_to_output(encoder);
+        struct drm_panel *panel = output->panel;
+
+        if (panel && panel->funcs) {
+                if (mode != DRM_MODE_DPMS_ON)
+                        drm_panel_disable(panel);
+                else
+                        drm_panel_enable(panel);
+        }
 }
 
 static bool tegra_encoder_mode_fixup(struct drm_encoder *encoder,
@@ -163,14 +184,23 @@ static irqreturn_t hpd_irq(int irq, void *data)
 
 int tegra_output_probe(struct tegra_output *output)
 {
+        struct device_node *ddc, *panel;
         enum of_gpio_flags flags;
-        struct device_node *ddc;
         size_t size;
         int err;
 
         if (!output->of_node)
                 output->of_node = output->dev->of_node;
 
+        panel = of_parse_phandle(output->of_node, "nvidia,panel", 0);
+        if (panel) {
+                output->panel = of_drm_find_panel(panel);
+                if (!output->panel)
+                        return -EPROBE_DEFER;
+
+                of_node_put(panel);
+        }
+
         output->edid = of_get_property(output->of_node, "nvidia,edid", &size);
 
         ddc = of_parse_phandle(output->of_node, "nvidia,ddc-i2c-bus", 0);
@@ -185,9 +215,6 @@ int tegra_output_probe(struct tegra_output *output)
                 of_node_put(ddc);
         }
 
-        if (!output->edid && !output->ddc)
-                return -ENODEV;
-
         output->hpd_gpio = of_get_named_gpio_flags(output->of_node,
                                                    "nvidia,hpd-gpio", 0,
                                                    &flags);
@@ -267,6 +294,9 @@ int tegra_output_init(struct drm_device *drm, struct tegra_output *output)
         drm_connector_helper_add(&output->connector, &connector_helper_funcs);
         output->connector.dpms = DRM_MODE_DPMS_OFF;
 
+        if (output->panel)
+                drm_panel_attach(output->panel, &output->connector);
+
         drm_encoder_init(drm, &output->encoder, &encoder_funcs, encoder);
         drm_encoder_helper_add(&output->encoder, &encoder_helper_funcs);