drm: automatic legacy gamma support

To support legacy gamma ioctls the drivers need to set
drm_crtc_funcs.gamma_set either to a custom implementation or to
drm_atomic_helper_legacy_gamma_set. Most of the atomic drivers do the
latter.

We can simplify this by making the core handle it automatically.

Move the drm_atomic_helper_legacy_gamma_set() functionality into
drm_color_mgmt.c to make drm_mode_gamma_set_ioctl() use
drm_crtc_funcs.gamma_set if set or GAMMA_LUT property if not.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201211114237.213288-2-tomi.valkeinen@ti.com

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -5452,7 +5452,6 @@ static void dm_disable_vblank(struct drm_crtc *crtc)
 static const struct drm_crtc_funcs amdgpu_dm_crtc_funcs = {
 	.reset = dm_crtc_reset_state,
 	.destroy = amdgpu_dm_crtc_destroy,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,
 	.atomic_duplicate_state = dm_crtc_duplicate_state,

drivers/gpu/drm/arm/display/komeda/komeda_crtc.c

@@ -550,7 +550,6 @@ static void komeda_crtc_vblank_disable(struct drm_crtc *crtc)
 }
 
 static const struct drm_crtc_funcs komeda_crtc_funcs = {
-	.gamma_set		= drm_atomic_helper_legacy_gamma_set,
 	.destroy		= drm_crtc_cleanup,
 	.set_config		= drm_atomic_helper_set_config,
 	.page_flip		= drm_atomic_helper_page_flip,

drivers/gpu/drm/arm/malidp_crtc.c

@@ -510,7 +510,6 @@ static void malidp_crtc_disable_vblank(struct drm_crtc *crtc)
 }
 
 static const struct drm_crtc_funcs malidp_crtc_funcs = {
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.destroy = drm_crtc_cleanup,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,

drivers/gpu/drm/armada/armada_crtc.c

@@ -820,7 +820,6 @@ static const struct drm_crtc_funcs armada_crtc_funcs = {
 	.cursor_set	= armada_drm_crtc_cursor_set,
 	.cursor_move	= armada_drm_crtc_cursor_move,
 	.destroy	= armada_drm_crtc_destroy,
-	.gamma_set	= drm_atomic_helper_legacy_gamma_set,
 	.set_config	= drm_atomic_helper_set_config,
 	.page_flip	= drm_atomic_helper_page_flip,
 	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,

drivers/gpu/drm/ast/ast_mode.c

@@ -903,7 +903,6 @@ static void ast_crtc_atomic_destroy_state(struct drm_crtc *crtc,
 
 static const struct drm_crtc_funcs ast_crtc_funcs = {
 	.reset = ast_crtc_reset,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.destroy = drm_crtc_cleanup,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c

@@ -473,7 +473,6 @@ static const struct drm_crtc_funcs atmel_hlcdc_crtc_funcs = {
 	.atomic_destroy_state = atmel_hlcdc_crtc_destroy_state,
 	.enable_vblank = atmel_hlcdc_crtc_enable_vblank,
 	.disable_vblank = atmel_hlcdc_crtc_disable_vblank,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 };
 
 int atmel_hlcdc_crtc_create(struct drm_device *dev)

drivers/gpu/drm/drm_atomic_helper.c

@@ -3508,76 +3508,6 @@ fail:
 }
 EXPORT_SYMBOL(drm_atomic_helper_page_flip_target);
 
-/**
- * drm_atomic_helper_legacy_gamma_set - set the legacy gamma correction table
- * @crtc: CRTC object
- * @red: red correction table
- * @green: green correction table
- * @blue: green correction table
- * @size: size of the tables
- * @ctx: lock acquire context
- *
- * Implements support for legacy gamma correction table for drivers
- * that support color management through the DEGAMMA_LUT/GAMMA_LUT
- * properties. See drm_crtc_enable_color_mgmt() and the containing chapter for
- * how the atomic color management and gamma tables work.
- */
-int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
-				       u16 *red, u16 *green, u16 *blue,
-				       uint32_t size,
-				       struct drm_modeset_acquire_ctx *ctx)
-{
-	struct drm_device *dev = crtc->dev;
-	struct drm_atomic_state *state;
-	struct drm_crtc_state *crtc_state;
-	struct drm_property_blob *blob = NULL;
-	struct drm_color_lut *blob_data;
-	int i, ret = 0;
-	bool replaced;
-
-	state = drm_atomic_state_alloc(crtc->dev);
-	if (!state)
-		return -ENOMEM;
-
-	blob = drm_property_create_blob(dev,
-					sizeof(struct drm_color_lut) * size,
-					NULL);
-	if (IS_ERR(blob)) {
-		ret = PTR_ERR(blob);
-		blob = NULL;
-		goto fail;
-	}
-
-	/* Prepare GAMMA_LUT with the legacy values. */
-	blob_data = blob->data;
-	for (i = 0; i < size; i++) {
-		blob_data[i].red = red[i];
-		blob_data[i].green = green[i];
-		blob_data[i].blue = blue[i];
-	}
-
-	state->acquire_ctx = ctx;
-	crtc_state = drm_atomic_get_crtc_state(state, crtc);
-	if (IS_ERR(crtc_state)) {
-		ret = PTR_ERR(crtc_state);
-		goto fail;
-	}
-
-	/* Reset DEGAMMA_LUT and CTM properties. */
-	replaced  = drm_property_replace_blob(&crtc_state->degamma_lut, NULL);
-	replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
-	replaced |= drm_property_replace_blob(&crtc_state->gamma_lut, blob);
-	crtc_state->color_mgmt_changed |= replaced;
-
-	ret = drm_atomic_commit(state);
-
-fail:
-	drm_atomic_state_put(state);
-	drm_property_blob_put(blob);
-	return ret;
-}
-EXPORT_SYMBOL(drm_atomic_helper_legacy_gamma_set);
-
 /**
  * drm_atomic_helper_bridge_propagate_bus_fmt() - Propagate output format to
  *						  the input end of a bridge

drivers/gpu/drm/drm_color_mgmt.c

@@ -22,6 +22,7 @@
 
 #include <linux/uaccess.h>
 
+#include <drm/drm_atomic.h>
 #include <drm/drm_color_mgmt.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
@@ -89,9 +90,8 @@
  *	modes) appropriately.
  *
  * There is also support for a legacy gamma table, which is set up by calling
- * drm_mode_crtc_set_gamma_size(). Drivers which support both should use
+ * drm_mode_crtc_set_gamma_size(). The DRM core will then alias the legacy gamma
- * drm_atomic_helper_legacy_gamma_set() to alias the legacy gamma ramp with the
+ * ramp with "GAMMA_LUT".
- * "GAMMA_LUT" property above.
  *
  * Support for different non RGB color encodings is controlled through
  * &drm_plane specific COLOR_ENCODING and COLOR_RANGE properties. They
@@ -156,9 +156,6 @@ EXPORT_SYMBOL(drm_color_ctm_s31_32_to_qm_n);
  * optional. The gamma and degamma properties are only attached if
  * their size is not 0 and ctm_property is only attached if has_ctm is
  * true.
- *
- * Drivers should use drm_atomic_helper_legacy_gamma_set() to implement the
- * legacy &drm_crtc_funcs.gamma_set callback.
  */
 void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
 				uint degamma_lut_size,
@@ -231,6 +228,102 @@ int drm_mode_crtc_set_gamma_size(struct drm_crtc *crtc,
 }
 EXPORT_SYMBOL(drm_mode_crtc_set_gamma_size);
 
+/**
+ * drm_crtc_supports_legacy_gamma - does the crtc support legacy gamma correction table
+ * @crtc: CRTC object
+ *
+ * Returns true/false if the given crtc supports setting the legacy gamma
+ * correction table.
+ */
+static bool drm_crtc_supports_legacy_gamma(struct drm_crtc *crtc)
+{
+	u32 gamma_id = crtc->dev->mode_config.gamma_lut_property->base.id;
+
+	if (!crtc->gamma_size)
+		return false;
+
+	if (crtc->funcs->gamma_set)
+		return true;
+
+	return !!drm_mode_obj_find_prop_id(&crtc->base, gamma_id);
+}
+
+/**
+ * drm_crtc_legacy_gamma_set - set the legacy gamma correction table
+ * @crtc: CRTC object
+ * @red: red correction table
+ * @green: green correction table
+ * @blue: green correction table
+ * @size: size of the tables
+ * @ctx: lock acquire context
+ *
+ * Implements support for legacy gamma correction table for drivers
+ * that have set drm_crtc_funcs.gamma_set or that support color management
+ * through the DEGAMMA_LUT/GAMMA_LUT properties. See
+ * drm_crtc_enable_color_mgmt() and the containing chapter for
+ * how the atomic color management and gamma tables work.
+ *
+ * This function sets the gamma using drm_crtc_funcs.gamma_set if set, or
+ * alternatively using crtc color management properties.
+ */
+static int drm_crtc_legacy_gamma_set(struct drm_crtc *crtc,
+				     u16 *red, u16 *green, u16 *blue,
+				     u32 size,
+				     struct drm_modeset_acquire_ctx *ctx)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_atomic_state *state;
+	struct drm_crtc_state *crtc_state;
+	struct drm_property_blob *blob;
+	struct drm_color_lut *blob_data;
+	int i, ret = 0;
+	bool replaced;
+
+	if (crtc->funcs->gamma_set)
+		return crtc->funcs->gamma_set(crtc, red, green, blue, size, ctx);
+
+	state = drm_atomic_state_alloc(crtc->dev);
+	if (!state)
+		return -ENOMEM;
+
+	blob = drm_property_create_blob(dev,
+					sizeof(struct drm_color_lut) * size,
+					NULL);
+	if (IS_ERR(blob)) {
+		ret = PTR_ERR(blob);
+		blob = NULL;
+		goto fail;
+	}
+
+	/* Prepare GAMMA_LUT with the legacy values. */
+	blob_data = blob->data;
+	for (i = 0; i < size; i++) {
+		blob_data[i].red = red[i];
+		blob_data[i].green = green[i];
+		blob_data[i].blue = blue[i];
+	}
+
+	state->acquire_ctx = ctx;
+	crtc_state = drm_atomic_get_crtc_state(state, crtc);
+	if (IS_ERR(crtc_state)) {
+		ret = PTR_ERR(crtc_state);
+		goto fail;
+	}
+
+	/* Set GAMMA_LUT and reset DEGAMMA_LUT and CTM */
+	replaced = drm_property_replace_blob(&crtc_state->degamma_lut, NULL);
+	replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
+	replaced |= drm_property_replace_blob(&crtc_state->gamma_lut, blob);
+	crtc_state->color_mgmt_changed |= replaced;
+
+	ret = drm_atomic_commit(state);
+
+fail:
+	drm_atomic_state_put(state);
+	drm_property_blob_put(blob);
+	return ret;
+}
+
 /**
  * drm_mode_gamma_set_ioctl - set the gamma table
  * @dev: DRM device
@@ -262,7 +355,7 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 	if (!crtc)
 		return -ENOENT;
 
-	if (crtc->funcs->gamma_set == NULL)
+	if (!drm_crtc_supports_legacy_gamma(crtc))
 		return -ENOSYS;
 
 	/* memcpy into gamma store */
@@ -290,8 +383,8 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 		goto out;
 	}
 
-	ret = crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
+	ret = drm_crtc_legacy_gamma_set(crtc, r_base, g_base, b_base,
-				     crtc->gamma_size, &ctx);
+					crtc->gamma_size, &ctx);
 
 out:
 	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);

drivers/gpu/drm/i915/display/intel_display.c

@@ -17267,7 +17267,6 @@ fail:
 }
 
 #define INTEL_CRTC_FUNCS \
-	.gamma_set = drm_atomic_helper_legacy_gamma_set, \
 	.set_config = drm_atomic_helper_set_config, \
 	.destroy = intel_crtc_destroy, \
 	.page_flip = drm_atomic_helper_page_flip, \

drivers/gpu/drm/ingenic/ingenic-drm-drv.c

@@ -774,8 +774,6 @@ static const struct drm_crtc_funcs ingenic_drm_crtc_funcs = {
 
 	.enable_vblank		= ingenic_drm_enable_vblank,
 	.disable_vblank		= ingenic_drm_disable_vblank,
-
-	.gamma_set		= drm_atomic_helper_legacy_gamma_set,
 };
 
 static const struct drm_plane_helper_funcs ingenic_drm_plane_helper_funcs = {

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -619,7 +619,6 @@ static const struct drm_crtc_funcs mtk_crtc_funcs = {
 	.reset			= mtk_drm_crtc_reset,
 	.atomic_duplicate_state	= mtk_drm_crtc_duplicate_state,
 	.atomic_destroy_state	= mtk_drm_crtc_destroy_state,
-	.gamma_set		= drm_atomic_helper_legacy_gamma_set,
 	.enable_vblank		= mtk_drm_crtc_enable_vblank,
 	.disable_vblank		= mtk_drm_crtc_disable_vblank,
 };

drivers/gpu/drm/nouveau/dispnv50/head.c

@@ -503,7 +503,6 @@ nv50_head_destroy(struct drm_crtc *crtc)
 static const struct drm_crtc_funcs
 nv50_head_func = {
 	.reset = nv50_head_reset,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.destroy = nv50_head_destroy,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,
@@ -518,7 +517,6 @@ nv50_head_func = {
 static const struct drm_crtc_funcs
 nvd9_head_func = {
 	.reset = nv50_head_reset,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.destroy = nv50_head_destroy,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,

drivers/gpu/drm/omapdrm/omap_crtc.c

@@ -741,7 +741,6 @@ static const struct drm_crtc_funcs omap_crtc_funcs = {
 	.set_config = drm_atomic_helper_set_config,
 	.destroy = omap_crtc_destroy,
 	.page_flip = drm_atomic_helper_page_flip,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.atomic_duplicate_state = omap_crtc_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
 	.atomic_set_property = omap_crtc_atomic_set_property,

drivers/gpu/drm/rcar-du/rcar_du_crtc.c

@@ -1144,7 +1144,6 @@ static const struct drm_crtc_funcs crtc_funcs_gen3 = {
 	.set_crc_source = rcar_du_crtc_set_crc_source,
 	.verify_crc_source = rcar_du_crtc_verify_crc_source,
 	.get_crc_sources = rcar_du_crtc_get_crc_sources,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 };
 
 /* -----------------------------------------------------------------------------

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -1643,7 +1643,6 @@ static const struct drm_crtc_funcs vop_crtc_funcs = {
 	.disable_vblank = vop_crtc_disable_vblank,
 	.set_crc_source = vop_crtc_set_crc_source,
 	.verify_crc_source = vop_crtc_verify_crc_source,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 };
 
 static void vop_fb_unref_worker(struct drm_flip_work *work, void *val)

drivers/gpu/drm/stm/ltdc.c

@@ -713,7 +713,6 @@ static const struct drm_crtc_funcs ltdc_crtc_funcs = {
 	.enable_vblank = ltdc_crtc_enable_vblank,
 	.disable_vblank = ltdc_crtc_disable_vblank,
 	.get_vblank_timestamp = drm_crtc_vblank_helper_get_vblank_timestamp,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 };
 
 /*

drivers/gpu/drm/vc4/vc4_crtc.c

@@ -871,7 +871,6 @@ static const struct drm_crtc_funcs vc4_crtc_funcs = {
 	.reset = vc4_crtc_reset,
 	.atomic_duplicate_state = vc4_crtc_duplicate_state,
 	.atomic_destroy_state = vc4_crtc_destroy_state,
-	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.enable_vblank = vc4_enable_vblank,
 	.disable_vblank = vc4_disable_vblank,
 	.get_vblank_timestamp = drm_crtc_vblank_helper_get_vblank_timestamp,

drivers/gpu/drm/vc4/vc4_txp.c

@@ -382,7 +382,6 @@ static const struct drm_crtc_funcs vc4_txp_crtc_funcs = {
 	.reset			= vc4_crtc_reset,
 	.atomic_duplicate_state	= vc4_crtc_duplicate_state,
 	.atomic_destroy_state	= vc4_crtc_destroy_state,
-	.gamma_set		= drm_atomic_helper_legacy_gamma_set,
 	.enable_vblank		= vc4_txp_enable_vblank,
 	.disable_vblank		= vc4_txp_disable_vblank,
 };

include/drm/drm_atomic_helper.h

@@ -147,10 +147,6 @@ int drm_atomic_helper_page_flip_target(
 				uint32_t flags,
 				uint32_t target,
 				struct drm_modeset_acquire_ctx *ctx);
-int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
-				       u16 *red, u16 *green, u16 *blue,
-				       uint32_t size,
-				       struct drm_modeset_acquire_ctx *ctx);
 
 /**
  * drm_atomic_crtc_for_each_plane - iterate over planes currently attached to CRTC