drm/probe-helper: Provide a TV get_modes helper

Most of the TV connectors will need a similar get_modes implementation
that will, depending on the drivers' capabilities, register the 480i and
576i modes.

That implementation will also need to set the preferred flag and order
the modes based on the driver and users preferrence.

This is especially important to guarantee that a userspace stack such as
Xorg can start and pick up the preferred mode while maintaining a
working output.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Tested-by: Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>
Acked-in-principle-or-something-like-that-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-12-256dad125326@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

1 files changed, 82 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index bcd9611dabfd..1ea053cef557 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -1146,3 +1146,85 @@ int drm_connector_helper_get_modes(struct drm_connector *connector)
 	return count;
 }
 EXPORT_SYMBOL(drm_connector_helper_get_modes);
+
+/**
+ * drm_connector_helper_tv_get_modes - Fills the modes availables to a TV connector
+ * @connector: The connector
+ *
+ * Fills the available modes for a TV connector based on the supported
+ * TV modes, and the default mode expressed by the kernel command line.
+ *
+ * This can be used as the default TV connector helper .get_modes() hook
+ * if the driver does not need any special processing.
+ *
+ * Returns:
+ * The number of modes added to the connector.
+ */
+int drm_connector_helper_tv_get_modes(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_property *tv_mode_property =
+		dev->mode_config.tv_mode_property;
+	struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
+	unsigned int ntsc_modes = BIT(DRM_MODE_TV_MODE_NTSC) |
+		BIT(DRM_MODE_TV_MODE_NTSC_443) |
+		BIT(DRM_MODE_TV_MODE_NTSC_J) |
+		BIT(DRM_MODE_TV_MODE_PAL_M);
+	unsigned int pal_modes = BIT(DRM_MODE_TV_MODE_PAL) |
+		BIT(DRM_MODE_TV_MODE_PAL_N) |
+		BIT(DRM_MODE_TV_MODE_SECAM);
+	unsigned int tv_modes[2] = { UINT_MAX, UINT_MAX };
+	unsigned int i, supported_tv_modes = 0;
+
+	if (!tv_mode_property)
+		return 0;
+
+	for (i = 0; i < tv_mode_property->num_values; i++)
+		supported_tv_modes |= BIT(tv_mode_property->values[i]);
+
+	if ((supported_tv_modes & ntsc_modes) &&
+	    (supported_tv_modes & pal_modes)) {
+		uint64_t default_mode;
+
+		if (drm_object_property_get_default_value(&connector->base,
+							  tv_mode_property,
+							  &default_mode))
+			return 0;
+
+		if (cmdline->tv_mode_specified)
+			default_mode = cmdline->tv_mode;
+
+		if (BIT(default_mode) & ntsc_modes) {
+			tv_modes[0] = DRM_MODE_TV_MODE_NTSC;
+			tv_modes[1] = DRM_MODE_TV_MODE_PAL;
+		} else {
+			tv_modes[0] = DRM_MODE_TV_MODE_PAL;
+			tv_modes[1] = DRM_MODE_TV_MODE_NTSC;
+		}
+	} else if (supported_tv_modes & ntsc_modes) {
+		tv_modes[0] = DRM_MODE_TV_MODE_NTSC;
+	} else if (supported_tv_modes & pal_modes) {
+		tv_modes[0] = DRM_MODE_TV_MODE_PAL;
+	} else {
+		return 0;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(tv_modes); i++) {
+		struct drm_display_mode *mode;
+
+		if (tv_modes[i] == DRM_MODE_TV_MODE_NTSC)
+			mode = drm_mode_analog_ntsc_480i(dev);
+		else if (tv_modes[i] == DRM_MODE_TV_MODE_PAL)
+			mode = drm_mode_analog_pal_576i(dev);
+		else
+			break;
+		if (!mode)
+			return i;
+		if (!i)
+			mode->type |= DRM_MODE_TYPE_PREFERRED;
+		drm_mode_probed_add(connector, mode);
+	}
+
+	return i;
+}
+EXPORT_SYMBOL(drm_connector_helper_tv_get_modes);