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.

Add two functions: drm_crtc_supports_legacy_gamma() which tells if the
legacy gamma table can be set, and drm_crtc_legacy_gamma_set() which
does the work by either calling the drm_crtc_funcs.gamma_set or using
GAMMA_LUT or DEGAMMA_LUT.

We can then drop drm_atomic_helper_legacy_gamma_set() and remove all its
uses.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

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

@@ -4910,7 +4910,6 @@ 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

@@ -544,7 +544,6 @@ 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

@@ -508,7 +508,6 @@ 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

@@ -814,7 +814,6 @@ 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

@@ -896,7 +896,6 @@ 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

@@ -472,7 +472,6 @@ 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

@@ -3499,85 +3499,6 @@ int drm_atomic_helper_page_flip_target(struct drm_crtc *crtc,
 }
 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.
- *
- * This function uses the GAMMA_LUT or DEGAMMA_LUT property for the gamma table.
- * GAMMA_LUT property is used if it exists, and DEGAMMA_LUT property is used as
- * a fallback.
- */
-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;
-
-	if (!crtc->has_gamma_prop && !crtc->has_degamma_prop)
-		return -ENODEV;
-
-	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/DEGAMMA_LUT and reset DEGAMMA/GAMMA_LUT and CTM */
-	replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
-					      crtc->has_gamma_prop ? NULL : blob);
-	replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
-	replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
-					      crtc->has_gamma_prop ? blob : NULL);
-	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_atomic_helper_legacy_gamma_set() to alias the legacy gamma ramp with the
- * "GAMMA_LUT" property above.
+ * drm_mode_crtc_set_gamma_size(). The DRM core will then alias the legacy gamma
+ * ramp with "GAMMA_LUT", or if that is unavailable "DEGAMMA_LUT".
  *
  * 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,
@@ -235,6 +232,109 @@ 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.
+ */
+bool drm_crtc_supports_legacy_gamma(struct drm_crtc *crtc)
+{
+	if (!crtc->gamma_size)
+		return false;
+
+	if (crtc->funcs->gamma_set)
+		return true;
+
+	return crtc->has_gamma_prop || crtc->has_degamma_prop;
+}
+EXPORT_SYMBOL(drm_crtc_supports_legacy_gamma);
+
+/**
+ * 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 the first one available:
+ * - drm_crtc_funcs.gamma_set()
+ * - GAMMA_LUT
+ * - DEGAMMA_LUT
+ */
+int drm_crtc_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;
+
+	if (crtc->funcs->gamma_set)
+		return crtc->funcs->gamma_set(crtc, red, green, blue, size, ctx);
+
+	if (!crtc->has_gamma_prop && !crtc->has_degamma_prop)
+		return -ENODEV;
+
+	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/DEGAMMA_LUT and reset DEGAMMA/GAMMA_LUT and CTM */
+	replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
+					      crtc->has_gamma_prop ? NULL : blob);
+	replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
+	replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
+					      crtc->has_gamma_prop ? blob : NULL);
+	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_crtc_legacy_gamma_set);
+
 /**
  * drm_mode_gamma_set_ioctl - set the gamma table
  * @dev: DRM device
@@ -266,7 +366,7 @@ 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 */
@@ -294,8 +394,8 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 		goto out;
 	}
 
-	ret = crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
-				     crtc->gamma_size, &ctx);
+	ret = drm_crtc_legacy_gamma_set(crtc, r_base, g_base, b_base,
+					crtc->gamma_size, &ctx);
 
 out:
 	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);

drivers/gpu/drm/drm_crtc_internal.h

@@ -114,6 +114,12 @@ int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
 const char *drm_get_color_encoding_name(enum drm_color_encoding encoding);
 const char *drm_get_color_range_name(enum drm_color_range range);
 
+bool drm_crtc_supports_legacy_gamma(struct drm_crtc *crtc);
+int drm_crtc_legacy_gamma_set(struct drm_crtc *crtc,
+			      u16 *red, u16 *green, u16 *blue,
+			      uint32_t size,
+			      struct drm_modeset_acquire_ctx *ctx);
+
 /* IOCTLs */
 int drm_mode_gamma_get_ioctl(struct drm_device *dev,
 			     void *data, struct drm_file *file_priv);

drivers/gpu/drm/drm_fb_helper.c

@@ -46,6 +46,7 @@
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 
+#include "drm_crtc_internal.h"
 #include "drm_crtc_helper_internal.h"
 #include "drm_internal.h"
 
@@ -136,15 +137,15 @@ static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
 {
 	uint16_t *r_base, *g_base, *b_base;
 
-	if (crtc->funcs->gamma_set == NULL)
+	if (!drm_crtc_supports_legacy_gamma(crtc))
 		return;
 
 	r_base = crtc->gamma_store;
 	g_base = r_base + crtc->gamma_size;
 	b_base = g_base + crtc->gamma_size;
 
-	crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
-			       crtc->gamma_size, NULL);
+	drm_crtc_legacy_gamma_set(crtc, r_base, g_base, b_base,
+				  crtc->gamma_size, NULL);
 }
 
 /**
@@ -907,7 +908,7 @@ static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
 	drm_modeset_lock_all(fb_helper->dev);
 	drm_client_for_each_modeset(modeset, &fb_helper->client) {
 		crtc = modeset->crtc;
-		if (!crtc->funcs->gamma_set || !crtc->gamma_size)
+		if (!drm_crtc_supports_legacy_gamma(crtc))
 			return -EINVAL;
 
 		if (cmap->start + cmap->len > crtc->gamma_size)
@@ -921,8 +922,8 @@ static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
 		memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
 		memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
 
-		ret = crtc->funcs->gamma_set(crtc, r, g, b,
-					     crtc->gamma_size, NULL);
+		ret = drm_crtc_legacy_gamma_set(crtc, r, g, b, crtc->gamma_size,
+						NULL);
 		if (ret)
 			return ret;
 	}

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

@@ -17273,7 +17273,6 @@ static int intel_crtc_late_register(struct drm_crtc *crtc)
 }
 
 #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

@@ -746,8 +746,6 @@ 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

@@ -614,7 +614,6 @@ 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

@@ -498,7 +498,6 @@ 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,
@@ -513,7 +512,6 @@ 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,