This patch clarifies the adjusted_mode documentation for bridges.
Signed-off-by: Philippe Cornu philippe.cornu@st.com Signed-off-by: Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com --- This patch follows discussions in: - "drm: clarify adjusted_mode for a bridge connected to a crtc" https://patchwork.freedesktop.org/patch/206801/ - "drm: bridge: Constify mode arguments to bridge .mode_set() operation" https://patchwork.freedesktop.org/patch/215449/
include/drm/drm_bridge.h | 16 ++++++++++++++++ include/drm/drm_crtc.h | 11 +++++++---- 2 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 3270fec46979..7d632c6a9214 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -178,6 +178,22 @@ struct drm_bridge_funcs { * then this would be &drm_encoder_helper_funcs.mode_set. The display * pipe (i.e. clocks and timing signals) is off when this function is * called. + * + * The adjusted_mode parameter corresponds to the mode output by the CRTC + * for the first bridge in the chain. It can be different from the mode + * parameter that contains the desired mode for the connector at the end + * of the bridges chain, for instance when the first bridge in the chain + * performs scaling. The adjusted mode is mostly useful for the first + * bridge in the chain and is likely irrelevant for the other bridges. + * + * For atomic drivers the adjusted_mode is the mode stored in + * &drm_crtc_state.adjusted_mode. + * + * NOTE: + * + * If a need arises to store and access modes adjusted for other locations + * than the connection between the CRTC and the first bridge, the DRM + * framework will have to be extended with DRM bridge states. */ void (*mode_set)(struct drm_bridge *bridge, struct drm_display_mode *mode, diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index a2d81d2907a9..65f749a9e9d3 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -134,10 +134,13 @@ struct drm_crtc_state { * * 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. + * is actually programmed into the hardware. + * + * For drivers using drm_bridge, this stores the hardware display timings + * used between the CRTC and the first bridge. For other drivers, the + * meaning of the adjusted_mode field is purely driver implementation + * defined information, and will usually be used to store the hardware + * display timings used between the CRTC and encoder blocks. */ struct drm_display_mode adjusted_mode;