From 4fd5e720b709b87f67809a871fde9fb6cb910f28 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 24 Jan 2022 23:16:33 +0100 Subject: drm/docs: Document where the C8 color lut is stored MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Also add notes that for atomic drivers it's really somewhere else and no longer in struct drm_crtc. Maybe we should put a bigger warning here that this is confusing, since the pixel format is a plane property, but the GAMMA_LUT property is on the crtc. But I think we can fix this if/when someone finds a need for a per-plane CLUT, since I'm not sure such hw even exists. I'm also not sure whether even hardware with a CLUT and a full color correction pipeline with degamm/cgm/gamma exists. Motivated by comments from Geert that we have a gap here. v2: More names for color luts (Laurent). Reviewed-by: Alex Deucher Cc: Laurent Pinchart Reviewed-by: Laurent Pinchart Cc: Geert Uytterhoeven Cc: Ville Syrjälä Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Daniel Vetter Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220124221633.952374-1-daniel.vetter@ffwll.ch --- include/drm/drm_crtc.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include') diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 13eeba2a750a..f9f9af8b5448 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -285,6 +285,10 @@ struct drm_crtc_state { * Lookup table for converting pixel data after the color conversion * matrix @ctm. See drm_crtc_enable_color_mgmt(). The blob (if not * NULL) is an array of &struct drm_color_lut. + * + * Note that for mostly historical reasons stemming from Xorg heritage, + * this is also used to store the color map (also sometimes color lut, + * CLUT or color palette) for indexed formats like DRM_FORMAT_C8. */ struct drm_property_blob *gamma_lut; @@ -1075,12 +1079,18 @@ struct drm_crtc { /** * @gamma_size: Size of legacy gamma ramp reported to userspace. Set up * by calling drm_mode_crtc_set_gamma_size(). + * + * Note that atomic drivers need to instead use + * &drm_crtc_state.gamma_lut. See drm_crtc_enable_color_mgmt(). */ uint32_t gamma_size; /** * @gamma_store: Gamma ramp values used by the legacy SETGAMMA and * GETGAMMA IOCTls. Set up by calling drm_mode_crtc_set_gamma_size(). + * + * Note that atomic drivers need to instead use + * &drm_crtc_state.gamma_lut. See drm_crtc_enable_color_mgmt(). */ uint16_t *gamma_store; -- cgit