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drm/doc: Document adjusted/request modes a bit better 

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 <laurent.pinchart@ideasonboard.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>
Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170515091136.26307-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2017-05-15 11:11:35 +02:00
parent 3eb220a531
commit 9de5d4a61c
3 changed files with 30 additions and 6 deletions
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2
include/drm/drm_bridge.h
View File

@ -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

28
include/drm/drm_crtc.h
View File

@ -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 */

6
include/drm/drm_modeset_helper_vtables.h
View File

@ -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.