[PATCH v2 1/2] drm: Introduce crtc->mode_valid() callback

[Jose Abreu]

Some crtc's may have restrictions in the mode they can display. In
this patch a new callback (crtc->mode_valid()) is introduced that
is called at the same stage of connector->mode_valid() callback.

This shall be implemented if the crtc has some sort of restriction
so that we don't probe modes that will fail in the commit() stage.
For example: A given crtc may be responsible to set a clock value.
If the clock can not produce all the values for the available
modes then this callback can be used to restrict the number of
probbed modes to only the ones that can be displayed.

If the crtc does not implement the callback then the behaviour will
remain the same. Also, for a given set of crtcs that can be bound to
the connector, if at least one can display the mode then the mode
will be probbed.

Signed-off-by: Jose Abreu <joabreu at synopsys.com>
Cc: Carlos Palminha <palminha at synopsys.com>
Cc: Alexey Brodkin <abrodkin at synopsys.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Dave Airlie <airlied at linux.ie>
Cc: Andrzej Hajda <a.hajda at samsung.com>
---

Changes v1->v2:
	- Correct indentation
	- Change function name to drm_validate_connector
	- Move connnector->mode_valid() to new function
	- Change crtc->mode_valid() "mode" field to const
	- Code reogarnization
	- Return earlier if crtc accepts mode

 drivers/gpu/drm/drm_probe_helper.c       | 50 ++++++++++++++++++++++++++++++--
 include/drm/drm_modeset_helper_vtables.h | 26 +++++++++++++++++
 2 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 1b0c14a..0741f36 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -80,6 +80,52 @@
 	return MODE_OK;
 }
 
+static enum drm_mode_status
+drm_mode_validate_connector(struct drm_connector *connector,
+			    struct drm_display_mode *mode)
+{
+	const struct drm_connector_helper_funcs *connector_funcs =
+		connector->helper_private;
+	struct drm_device *dev = connector->dev;
+	uint32_t *ids = connector->encoder_ids;
+	enum drm_mode_status ret = MODE_OK;
+	unsigned int i;
+
+	/* Step 1: Validate against connector */
+	if (connector_funcs->mode_valid)
+		ret = connector_funcs->mode_valid(connector, mode);
+
+	if (ret != MODE_OK)
+		return ret;
+
+	/* Step 2: Validate against crtc's */
+	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
+		struct drm_encoder *encoder = drm_encoder_find(dev, ids[i]);
+		struct drm_crtc *crtc;
+
+		if (!encoder)
+			continue;
+
+		drm_for_each_crtc(crtc, dev) {
+			const struct drm_crtc_helper_funcs *crtc_funcs;
+
+			if (!drm_encoder_crtc_ok(encoder, crtc))
+				continue;
+
+			crtc_funcs = crtc->helper_private;
+			if (!crtc_funcs || !crtc_funcs->mode_valid)
+				return MODE_OK; /* crtc accepts everything */
+
+			ret = crtc_funcs->mode_valid(crtc, mode);
+			if (ret == MODE_OK)
+				return ret;
+		}
+	}
+
+	/* NOTE: If no crtc or encoder is found then we return MODE_OK */
+	return ret;
+}
+
 static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
 {
 	struct drm_cmdline_mode *cmdline_mode;
@@ -428,8 +474,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		if (mode->status == MODE_OK)
 			mode->status = drm_mode_validate_flag(mode, mode_flags);
 
-		if (mode->status == MODE_OK && connector_funcs->mode_valid)
-			mode->status = connector_funcs->mode_valid(connector,
+		if (mode->status == MODE_OK)
+			mode->status = drm_mode_validate_connector(connector,
 								   mode);
 	}
 
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index c01c328..ecb055c 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -106,6 +106,32 @@ struct drm_crtc_helper_funcs {
 	void (*commit)(struct drm_crtc *crtc);
 
 	/**
+	 * @mode_valid:
+	 *
+	 * This callback should be implemented if the crtc has some sort of
+	 * restriction in the modes it can display. For example, a given crtc
+	 * may be responsible to set a clock value. If the clock can not
+	 * produce all the values for the available modes then this callback
+	 * can be used to restrict the number of probbed modes to only the ones
+	 * that can be displayed.
+	 *
+	 * This is directly called at the same stage of connector->mode_valid
+	 * callback.
+	 *
+	 * NOTE:
+	 *
+	 * For a given set of crtc's in a drm_device, if at least one does not
+	 * have the mode_valid callback, or, at least one returns MODE_OK then
+	 * the mode will be probbed.
+	 *
+	 * RETURNS:
+	 *
+	 * drm_mode_status Enum
+	 */
+	enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
+					   const struct drm_display_mode *mode);
+
+	/**
 	 * @mode_fixup:
 	 *
 	 * This callback is used to validate a mode. The parameter mode is the
-- 
1.9.1