Re: [PATCH v3 1/2] drm: automatic legacy gamma support

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Dec 10, 2020 at 04:27:39PM +0100, Daniel Vetter wrote:
> On Thu, Dec 10, 2020 at 04:08:51PM +0200, Tomi Valkeinen wrote:
> > 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 three functions to drm_color_mgmt.c:
> > 
> > drm_crtc_supports_legacy_gamma() which tells if the driver supports
> > setting the legacy gamma.
> > 
> > drm_crtc_gamma_ramp_set() which sets the given gamma ramp to GAMMA_LUT
> > and resets DEGAMMA_LUT and CTM.
> > 
> > drm_crtc_legacy_gamma_set() which sets the given gamma ramp values
> > either using drm_crtc_funcs.gamma_set or drm_crtc_gamma_ramp_set().
> > 
> > These functions are used from the drm_mode_gamma_set_ioctl, and from
> > drm_fb_helper.c when it is dealing with fbdev cmap.
> > 
> > We can then drop drm_atomic_helper_legacy_gamma_set() and remove all its
> > uses.
> > 
> > Note that we need to EXPORT_SYMBOL all the new functions as they are
> > used from drm_fb_helper, but they are declared in drm_crtc_internal.h as
> > they are not supposed to be used by the drivers.
> > 
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> > ---
> >  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |   1 -
> >  .../gpu/drm/arm/display/komeda/komeda_crtc.c  |   1 -
> >  drivers/gpu/drm/arm/malidp_crtc.c             |   1 -
> >  drivers/gpu/drm/armada/armada_crtc.c          |   1 -
> >  drivers/gpu/drm/ast/ast_mode.c                |   1 -
> >  .../gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c    |   1 -
> >  drivers/gpu/drm/drm_atomic_helper.c           |  70 ---------
> >  drivers/gpu/drm/drm_color_mgmt.c              | 138 ++++++++++++++++--
> >  drivers/gpu/drm/drm_crtc_internal.h           |  10 ++
> >  drivers/gpu/drm/drm_fb_helper.c               |  28 ++--
> >  drivers/gpu/drm/i915/display/intel_display.c  |   1 -
> >  drivers/gpu/drm/ingenic/ingenic-drm-drv.c     |   2 -
> >  drivers/gpu/drm/mediatek/mtk_drm_crtc.c       |   1 -
> >  drivers/gpu/drm/nouveau/dispnv50/head.c       |   2 -
> >  drivers/gpu/drm/omapdrm/omap_crtc.c           |   1 -
> >  drivers/gpu/drm/rcar-du/rcar_du_crtc.c        |   1 -
> >  drivers/gpu/drm/rockchip/rockchip_drm_vop.c   |   1 -
> >  drivers/gpu/drm/stm/ltdc.c                    |   1 -
> >  drivers/gpu/drm/vc4/vc4_crtc.c                |   1 -
> >  drivers/gpu/drm/vc4/vc4_txp.c                 |   1 -
> >  include/drm/drm_atomic_helper.h               |   4 -
> >  include/drm/drm_color_mgmt.h                  |   1 -
> >  22 files changed, 148 insertions(+), 121 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index 2855bb918535..848b06c51b0e 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -5396,7 +5396,6 @@ 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,
> > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > index 4b485eb512e2..59172acb9738 100644
> > --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > +++ b/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,
> > diff --git a/drivers/gpu/drm/arm/malidp_crtc.c b/drivers/gpu/drm/arm/malidp_crtc.c
> > index 108e7a31bd26..494075ddbef6 100644
> > --- a/drivers/gpu/drm/arm/malidp_crtc.c
> > +++ b/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,
> > diff --git a/drivers/gpu/drm/armada/armada_crtc.c b/drivers/gpu/drm/armada/armada_crtc.c
> > index 3ebcf5a52c8b..b7bb90ae787f 100644
> > --- a/drivers/gpu/drm/armada/armada_crtc.c
> > +++ b/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,
> > diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> > index 9db371f4054f..5b0ec785c516 100644
> > --- a/drivers/gpu/drm/ast/ast_mode.c
> > +++ b/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,
> > diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> > index c58fa00b4848..05ad75d155e8 100644
> > --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> > +++ b/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)
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index ba1507036f26..b114658100b3 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -3499,76 +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.
> > - */
> > -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
> > diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
> > index 3bcabc2f6e0e..c4e4d59c4432 100644
> > --- a/drivers/gpu/drm/drm_color_mgmt.c
> > +++ b/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".
> >   *
> >   * 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 +228,129 @@ 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)
> > +{
> > +	uint32_t 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);
> > +}
> > +EXPORT_SYMBOL(drm_crtc_supports_legacy_gamma);
> > +
> > +/**
> > + * drm_crtc_gamma_ramp_set - set gamma ramp using GAMMA_LUT property
> > + * @state: atomic state to which the gamma ramp is set
> > + * @crtc: CRTC object
> > + * @blob: property blob for the gamma ramp
> > + *
> > + * Set given gamma ramp to the crtc using GAMMA_LUT property and resetting
> > + * DEGAMMA_LUT and CTM.
> > + */
> > +int drm_crtc_gamma_ramp_set(struct drm_atomic_state *state, struct drm_crtc *crtc,
> > +		       struct drm_property_blob *blob)
> > +{
> > +	struct drm_crtc_state *crtc_state;
> > +	struct drm_property_blob *gamma_blob;
> > +	struct drm_property_blob *degamma_blob;
> > +	bool replaced;
> > +
> > +	gamma_blob = blob;
> > +	degamma_blob = NULL;
> > +
> > +	crtc_state = drm_atomic_get_crtc_state(state, crtc);
> > +	if (IS_ERR(crtc_state))
> > +		return PTR_ERR(crtc_state);
> > +
> > +	/* Set GAMMA_LUT and reset DEGAMMA_LUT and CTM */
> > +	replaced = drm_property_replace_blob(&crtc_state->degamma_lut, degamma_blob);
> > +	replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
> > +	replaced |= drm_property_replace_blob(&crtc_state->gamma_lut, gamma_blob);
> > +	crtc_state->color_mgmt_changed |= replaced;
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL(drm_crtc_gamma_ramp_set);
> > +
> > +/**
> > + * 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.
> > + */
> > +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_property_blob *blob;
> > +	struct drm_color_lut *blob_data;
> > +	int i, ret = 0;
> > +
> > +	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;
> > +
> > +	ret = drm_crtc_gamma_ramp_set(state, crtc, blob);
> > +	if (ret)
> > +		goto fail;
> > +
> > +	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
> > @@ -262,7 +382,7 @@ 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 +410,8 @@ 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);
> > diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
> > index 54d4cf1233e9..74856df6482a 100644
> > --- a/drivers/gpu/drm/drm_crtc_internal.h
> > +++ b/drivers/gpu/drm/drm_crtc_internal.h
> > @@ -51,9 +51,11 @@ struct drm_mode_fb_cmd2;
> >  struct drm_mode_fb_cmd;
> >  struct drm_mode_object;
> >  struct drm_mode_set;
> > +struct drm_modeset_acquire_ctx;
> >  struct drm_plane;
> >  struct drm_plane_state;
> >  struct drm_property;
> > +struct drm_property_blob;
> >  struct edid;
> >  struct kref;
> >  struct work_struct;
> > @@ -114,6 +116,14 @@ 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_gamma_ramp_set(struct drm_atomic_state *state, struct drm_crtc *crtc,
> > +		       struct drm_property_blob *blob);
> > +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);
> > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> > index e82db0f4e771..80e3797f0f01 100644
> > --- a/drivers/gpu/drm/drm_fb_helper.c
> > +++ b/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"
> 
> So this is a bit annoying, because thus far we managed to have a very
> clear split between core and helpers. And I think we can keep that.
> 
> >  #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);
> 
> This is only used by legacy non-atomic drivers. It's pretty much
> impossible to make kgdb work with atomic drivers, so really let's just not
> bother and keep the code as-is.
> 
> >  }
> >  
> >  /**
> > @@ -946,7 +947,7 @@ 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)) {
> >  			ret = -EINVAL;
> >  			goto out;
> >  		}
> > @@ -964,8 +965,8 @@ 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)
> >  			goto out;
> 
> Same here.
> 
> >  	}
> > @@ -1024,12 +1025,10 @@ static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info)
> >  	struct drm_device *dev = fb_helper->dev;
> >  	struct drm_property_blob *gamma_lut = NULL;
> >  	struct drm_modeset_acquire_ctx ctx;
> > -	struct drm_crtc_state *crtc_state;
> >  	struct drm_atomic_state *state;
> >  	struct drm_mode_set *modeset;
> >  	struct drm_crtc *crtc;
> >  	u16 *r, *g, *b;
> > -	bool replaced;
> >  	int ret = 0;
> >  
> >  	drm_modeset_acquire_init(&ctx, 0);
> > @@ -1053,18 +1052,9 @@ static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info)
> >  			goto out_state;
> >  		}
> >  
> > -		crtc_state = drm_atomic_get_crtc_state(state, crtc);
> > -		if (IS_ERR(crtc_state)) {
> > -			ret = PTR_ERR(crtc_state);
> > +		ret = drm_crtc_gamma_ramp_set(state, crtc, gamma_lut);
> > +		if (ret)
> 
> You're nesting an atomic commit in an atomic commit here, that will go
> boom. I guess ideally we'd move this into drm_client_modeset so it
> remembers the fbdev gamma ramp and does it all in one go.

IIRC that's pretty much what's in my branch that I mentioned earlier.
Mentioning it again in case someone wants a leg up for implementing
this idea ;)

-- 
Ville Syrjälä
Intel
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