From 9de5d4a61cc2a99634e3b51bda0f8e2fdd8f4287 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 15 May 2017 11:11:35 +0200 Subject: [PATCH] drm/doc: Document adjusted/request modes a bit better MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Laurent started a massive discussion on IRC about this. Let's try to document common usage a bit better. v2: Cross-links+typos. Cc: Laurent Pinchart Cc: Ville Syrjälä Cc: Jose Abreu Reviewed-by: Jose Abreu Reviewed-by: Andrzej Hajda Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20170515091136.26307-1-daniel.vetter@ffwll.ch --- include/drm/drm_bridge.h | 2 +- include/drm/drm_crtc.h | 28 +++++++++++++++++++++--- include/drm/drm_modeset_helper_vtables.h | 6 +++-- 3 files changed, 30 insertions(+), 6 deletions(-) diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index f703bafc2e30..983054f2e86e 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -100,7 +100,7 @@ struct drm_bridge_funcs { * the display chain, either the final &drm_connector or the next * &drm_bridge. The parameter adjusted_mode is the input mode the bridge * requires. It can be modified by this callback and does not need to - * match mode. + * match mode. See also &drm_crtc_state.adjusted_mode for more details. * * This is the only hook that allows a bridge to reject a modeset. If * this function passes all other callbacks must succeed for this diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index adf4e91a9399..b6e3713bd7a9 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -90,8 +90,6 @@ struct drm_plane_helper_funcs; * @plane_mask: bitmask of (1 << drm_plane_index(plane)) of attached planes * @connector_mask: bitmask of (1 << drm_connector_index(connector)) of attached connectors * @encoder_mask: bitmask of (1 << drm_encoder_index(encoder)) of attached encoders - * @adjusted_mode: for use by helpers and drivers to compute adjusted mode timings - * @mode: current mode timings * @mode_blob: &drm_property_blob for @mode * @state: backpointer to global drm_atomic_state * @@ -131,9 +129,33 @@ struct drm_crtc_state { u32 connector_mask; u32 encoder_mask; - /* adjusted_mode: for use by helpers and drivers */ + /** + * @adjusted_mode: + * + * Internal display timings which can be used by the driver to handle + * differences between the mode requested by userspace in @mode and what + * is actually programmed into the hardware. It is purely driver + * implementation defined what exactly this adjusted mode means. Usually + * it is used to store the hardware display timings used between the + * CRTC and encoder blocks. + */ struct drm_display_mode adjusted_mode; + /** + * @mode: + * + * Display timings requested by userspace. The driver should try to + * match the refresh rate as close as possible (but note that it's + * undefined what exactly is close enough, e.g. some of the HDMI modes + * only differ in less than 1% of the refresh rate). The active width + * and height as observed by userspace for positioning planes must match + * exactly. + * + * For external connectors where the sink isn't fixed (like with a + * built-in panel), this mode here should match the physical mode on the + * wire to the last details (i.e. including sync polarities and + * everything). + */ struct drm_display_mode mode; /* blob property to expose current mode to atomic userspace */ diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h index 739b832eb304..361240ca738e 100644 --- a/include/drm/drm_modeset_helper_vtables.h +++ b/include/drm/drm_modeset_helper_vtables.h @@ -147,7 +147,8 @@ struct drm_crtc_helper_funcs { * encoders need to be fed with. Note that this is the inverse semantics * of the meaning for the &drm_encoder and &drm_bridge_funcs.mode_fixup * vfunc. If the CRTC cannot support the requested conversion from mode - * to adjusted_mode it should reject the modeset. + * to adjusted_mode it should reject the modeset. See also + * &drm_crtc_state.adjusted_mode for more details. * * This function is used by both legacy CRTC helpers and atomic helpers. * With atomic helpers it is optional. @@ -528,7 +529,8 @@ struct drm_encoder_helper_funcs { * mode is the display mode that should be fed to the next element in * the display chain, either the final &drm_connector or a &drm_bridge. * The parameter adjusted_mode is the input mode the encoder requires. It - * can be modified by this callback and does not need to match mode. + * can be modified by this callback and does not need to match mode. See + * also &drm_crtc_state.adjusted_mode for more details. * * This function is used by both legacy CRTC helpers and atomic helpers. * This hook is optional.