Hi,
On Thu, Sep 8, 2016 at 8:17 PM, Maxime Ripard maxime.ripard@free-electrons.com wrote:
Some boards have an entirely passive RGB to VGA bridge, based on either DACs or resistor ladders.
Those might or might not have an i2c bus routed to the VGA connector in order to access the screen EDIDs.
Add a bridge that doesn't do anything but expose the modes available on the screen, either based on the EDIDs if available, or based on the XGA standards.
Acked-by: Rob Herring robh@kernel.org Signed-off-by: Maxime Ripard maxime.ripard@free-electrons.com
.../bindings/display/bridge/rgb-to-vga-bridge.txt | 52 +++++ drivers/gpu/drm/bridge/Kconfig | 6 + drivers/gpu/drm/bridge/Makefile | 1 + drivers/gpu/drm/bridge/rgb-to-vga.c | 232 +++++++++++++++++++++ 4 files changed, 291 insertions(+) create mode 100644 Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt create mode 100644 drivers/gpu/drm/bridge/rgb-to-vga.c
diff --git a/Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt b/Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt new file mode 100644 index 000000000000..83a053fb51a0 --- /dev/null +++ b/Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt @@ -0,0 +1,52 @@ +Passive RGB to VGA bridge +-------------------------
+This binding is aimed for entirely passive RGB to VGA bridges that do not +require any configuration.
+Required properties:
+- compatible: Must be "rgb-to-vga-bridge"
+Required nodes:
+This device has two video ports. Their connections are modeled using the OF +graph bindings specified in Documentation/devicetree/bindings/graph.txt.
+- Video port 0 for RGB input +- Video port 1 for VGA output
+Example +-------
+bridge {
compatible = "rgb-to-vga-bridge";#address-cells = <1>;#size-cells = <0>;ports {#address-cells = <1>;#size-cells = <0>;port@0 {#address-cells = <1>;#size-cells = <0>;reg = <0>;vga_bridge_in: endpoint {remote-endpoint = <&tcon0_out_vga>;};};port@1 {#address-cells = <1>;#size-cells = <0>;reg = <1>;vga_bridge_out: endpoint {remote-endpoint = <&vga_con_in>;};};};+}; diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig index b590e678052d..42b95adf5091 100644 --- a/drivers/gpu/drm/bridge/Kconfig +++ b/drivers/gpu/drm/bridge/Kconfig @@ -17,6 +17,12 @@ config DRM_ANALOGIX_ANX78XX the HDMI output of an application processor to MyDP or DisplayPort.
+config DRM_RGB_TO_VGA
tristate "Dumb RGB to VGA Bridge support"select DRM_KMS_HELPERhelpSupport for passive RGB to VGA bridgesconfig DRM_DW_HDMI tristate select DRM_KMS_HELPER diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile index efdb07e878f5..3bb8cbe09fe9 100644 --- a/drivers/gpu/drm/bridge/Makefile +++ b/drivers/gpu/drm/bridge/Makefile @@ -1,6 +1,7 @@ ccflags-y := -Iinclude/drm
obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o +obj-$(CONFIG_DRM_RGB_TO_VGA) += rgb-to-vga.o obj-$(CONFIG_DRM_DW_HDMI) += dw-hdmi.o obj-$(CONFIG_DRM_DW_HDMI_AHB_AUDIO) += dw-hdmi-ahb-audio.o obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o diff --git a/drivers/gpu/drm/bridge/rgb-to-vga.c b/drivers/gpu/drm/bridge/rgb-to-vga.c new file mode 100644 index 000000000000..84b1b10198a4 --- /dev/null +++ b/drivers/gpu/drm/bridge/rgb-to-vga.c @@ -0,0 +1,232 @@
No beginning file header / copyright statement?
+#include <linux/module.h> +#include <linux/of_graph.h>
+#include <drm/drmP.h> +#include <drm/drm_atomic_helper.h> +#include <drm/drm_crtc.h> +#include <drm/drm_crtc_helper.h>
+struct dumb_vga {
struct drm_bridge bridge;struct drm_connector connector;struct i2c_adapter *ddc;+};
+static inline struct dumb_vga * +drm_bridge_to_dumb_vga(struct drm_bridge *bridge) +{
return container_of(bridge, struct dumb_vga, bridge);+}
+static inline struct dumb_vga * +drm_connector_to_dumb_vga(struct drm_connector *connector) +{
return container_of(connector, struct dumb_vga, connector);+}
+static int dumb_vga_get_modes(struct drm_connector *connector) +{
struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);struct edid *edid;int ret;if (IS_ERR(vga->ddc))goto fallback;edid = drm_get_edid(connector, vga->ddc);if (!edid) {DRM_INFO("EDID readout failed, falling back to standard modes\n");goto fallback;}drm_mode_connector_update_edid_property(connector, edid);return drm_add_edid_modes(connector, edid);+fallback:
/** In case we cannot retrieve the EDIDs (broken or missing i2c* bus), fallback on the XGA standards*/ret = drm_add_modes_noedid(connector, 1920, 1200);/* And prefer a mode pretty much anyone can handle */drm_set_preferred_mode(connector, 1024, 768);return ret;+}
+static struct drm_encoder * +dumb_vga_best_encoder(struct drm_connector *connector) +{
struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);return vga->bridge.encoder;+}
+static struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
.get_modes = dumb_vga_get_modes,.best_encoder = dumb_vga_best_encoder,
drm_modeset_helper_vtables.h says the following about .best_encoder:
You can leave this function to NULL if the connector is only attached to a single encoder and you are using the atomic helpers. In this case, the core will call drm_atomic_helper_best_encoder() for you.
IMHO you can drop the callback here.
+};
+static enum drm_connector_status +dumb_vga_connector_detect(struct drm_connector *connector, bool force) +{
struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);/** Even if we have an I2C bus, we can't assume that the cable* is disconnected if drm_probe_ddc. Some cables don't wire* the DDC pins, or the I2C bus might be disfunctional.*/if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))return connector_status_connected;return connector_status_unknown;+}
+static void +dumb_vga_connector_destroy(struct drm_connector *connector) +{
drm_connector_cleanup(connector);+}
+static struct drm_connector_funcs dumb_vga_con_funcs = {
.dpms = drm_atomic_helper_connector_dpms,.detect = dumb_vga_connector_detect,.fill_modes = drm_helper_probe_single_connector_modes,.destroy = dumb_vga_connector_destroy,.reset = drm_atomic_helper_connector_reset,.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,+};
+static int dumb_vga_attach(struct drm_bridge *bridge) +{
struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);int ret;if (!bridge->encoder) {DRM_ERROR("Missing encoder\n");return -ENODEV;}drm_connector_helper_add(&vga->connector,&dumb_vga_con_helper_funcs);ret = drm_connector_init(bridge->dev, &vga->connector,&dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);if (ret) {DRM_ERROR("Failed to initialize connector\n");return ret;}drm_mode_connector_attach_encoder(&vga->connector,bridge->encoder);return 0;+}
+static void dumb_vga_nop(struct drm_bridge *bridge) {};
+static struct drm_bridge_funcs dumb_vga_bridge_funcs = {
const?
.attach = dumb_vga_attach,.enable = dumb_vga_nop,.disable = dumb_vga_nop,.pre_enable = dumb_vga_nop,.post_disable = dumb_vga_nop,
Nit: The 4 nops can be dropped. The header file states these callbacks are optional.
+};
+static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev) +{
struct device_node *end_node, *phandle, *remote;struct i2c_adapter *ddc;end_node = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);if (!end_node) {dev_err(dev, "Missing connector endpoint\n");return ERR_PTR(-ENODEV);}remote = of_graph_get_remote_port_parent(end_node);of_node_put(end_node);if (!remote) {dev_err(dev, "Enable to parse remote node\n");return ERR_PTR(-EINVAL);}phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);of_node_put(remote);if (!phandle)return ERR_PTR(-ENODEV);ddc = of_get_i2c_adapter_by_node(phandle);of_node_put(phandle);if (!ddc)return ERR_PTR(-EPROBE_DEFER);return ddc;+}
+static int dumb_vga_probe(struct platform_device *pdev) +{
struct dumb_vga *vga;int ret;vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);if (!vga)return -ENOMEM;platform_set_drvdata(pdev, vga);vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);if (IS_ERR(vga->ddc)) {if (PTR_ERR(vga->ddc) == -ENODEV) {dev_info(&pdev->dev,"No i2c bus specified... Disabling EDID readout\n");} else {dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");return PTR_ERR(vga->ddc);}}vga->bridge.funcs = &dumb_vga_bridge_funcs;vga->bridge.of_node = pdev->dev.of_node;ret = drm_bridge_add(&vga->bridge);if (ret && !IS_ERR(vga->ddc))i2c_put_adapter(vga->ddc);return ret;+}
+static int dumb_vga_remove(struct platform_device *pdev) +{
struct dumb_vga *vga = platform_get_drvdata(pdev);drm_bridge_remove(&vga->bridge);if (!IS_ERR(vga->ddc))i2c_put_adapter(vga->ddc);return 0;+}
+static const struct of_device_id dumb_vga_match[] = {
{ .compatible = "rgb-to-vga-bridge" },{},+}; +MODULE_DEVICE_TABLE(of, dumb_vga_match);
+struct platform_driver dumb_vga_driver = {
.probe = dumb_vga_probe,.remove = dumb_vga_remove,.driver = {.name = "rgb-to-vga-bridge",.of_match_table = dumb_vga_match,},+}; +module_platform_driver(dumb_vga_driver);
+MODULE_AUTHOR("Maxime Ripard maxime.ripard@free-electrons.com"); +MODULE_DESCRIPTION("Dumb RGB to VGA bridge driver"); +MODULE_LICENSE("GPL");
FWIW the rest looks fine.
Regards ChenYu