[PATCH 1/3] drm: Introduce scaling filter mode property

[Shashank Sharma]

This patch adds a scaling filter mode porperty
to allow:
- A driver/HW to showcase it's scaling filter capabilities.
- A userspace to pick a desired effect while scaling.

This option will be particularly useful in the scenarios where
Integer mode scaling is possible, and a UI client wants to pick
filters like Nearest-neighbor applied for non-blurry outputs.

There was a RFC patch series published, to discus the request to enable
Integer mode scaling by some of the gaming communities, which can be
found here:
https://patchwork.freedesktop.org/series/66175/

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c |  4 ++++
 include/drm/drm_crtc.h            | 26 ++++++++++++++++++++++++++
 include/drm/drm_mode_config.h     |  6 ++++++
 3 files changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 0d466d3b0809..883329453a86 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -435,6 +435,8 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
 		return ret;
 	} else if (property == config->prop_vrr_enabled) {
 		state->vrr_enabled = val;
+	} else if (property == config->scaling_filter_property) {
+		state->scaling_filter = val;
 	} else if (property == config->degamma_lut_property) {
 		ret = drm_atomic_replace_property_blob_from_id(dev,
 					&state->degamma_lut,
@@ -503,6 +505,8 @@ drm_atomic_crtc_get_property(struct drm_crtc *crtc,
 		*val = (state->gamma_lut) ? state->gamma_lut->base.id : 0;
 	else if (property == config->prop_out_fence_ptr)
 		*val = 0;
+	else if (property == config->scaling_filter_property)
+		*val = state->scaling_filter;
 	else if (crtc->funcs->atomic_get_property)
 		return crtc->funcs->atomic_get_property(crtc, state, property, val);
 	else
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 5e9b15a0e8c5..94c5509474a8 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -58,6 +58,25 @@ struct device_node;
 struct dma_fence;
 struct edid;
 
+enum drm_scaling_filters {
+	DRM_SCALING_FILTER_DEFAULT,
+	DRM_SCALING_FILTER_MEDIUM,
+	DRM_SCALING_FILTER_BILINEAR,
+	DRM_SCALING_FILTER_NN,
+	DRM_SCALING_FILTER_NN_IS_ONLY,
+	DRM_SCALING_FILTER_EDGE_ENHANCE,
+	DRM_SCALING_FILTER_INVALID,
+};
+
+static const struct drm_prop_enum_list drm_scaling_filter_enum_list[] = {
+	{ DRM_SCALING_FILTER_DEFAULT, "Default" },
+	{ DRM_SCALING_FILTER_MEDIUM, "Medium" },
+	{ DRM_SCALING_FILTER_BILINEAR, "Bilinear" },
+	{ DRM_SCALING_FILTER_NN, "Nearest Neighbor" },
+	{ DRM_SCALING_FILTER_NN_IS_ONLY, "Integer Mode Scaling" },
+	{ DRM_SCALING_FILTER_INVALID, "Invalid" },
+};
+
 static inline int64_t U642I64(uint64_t val)
 {
 	return (int64_t)*((int64_t *)&val);
@@ -283,6 +302,13 @@ struct drm_crtc_state {
 	 */
 	u32 target_vblank;
 
+	/**
+	 * @scaling_filter:
+	 *
+	 * Scaling filter mode to be applied
+	 */
+	u32 scaling_filter;
+
 	/**
 	 * @async_flip:
 	 *
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index 3bcbe30339f0..efd6fd55770f 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -914,6 +914,12 @@ struct drm_mode_config {
 	 */
 	struct drm_property *modifiers_property;
 
+	/**
+	 * @scaling_filter_property: CRTC property to apply a particular filter
+	 * while scaling in panel fitter mode.
+	 */
+	struct drm_property *scaling_filter_property;
+
 	/* cursor size */
 	uint32_t cursor_width, cursor_height;
 
-- 
2.17.1