Add optional drm_crtc_helper_funcs.select_output_bus_format callback. This callback allows to negotiate compatible media bus format on the link between CRTC and connected DRM encoder or DRM bridge chain. A good usage example is the CRTC implemented as FPGA soft IP. This kind of CRTC will most certainly support a single output media bus format, as supporting multiple runtime options consumes extra FPGA resources. A variety of options for the FPGA designs are usually achieved by synthesizing IP with different parameters. Add drm_helper_crtc_select_output_bus_format that wraps drm_crtc_helper_funcs.select_output_bus_format. Incorporate select_output_bus_format callback into the format negotiation stage to fix the input bus format of the first DRM bridge in the chain. Save negotiated output media bus format in drm_crtc_state. Signed-off-by: Anatoliy Klymenko <anatoliy.klymenko@xxxxxxx> --- drivers/gpu/drm/drm_bridge.c | 14 ++++++++++-- drivers/gpu/drm/drm_crtc_helper.c | 38 ++++++++++++++++++++++++++++++++ include/drm/drm_crtc.h | 11 +++++++++ include/drm/drm_crtc_helper.h | 5 +++++ include/drm/drm_modeset_helper_vtables.h | 30 +++++++++++++++++++++++++ 5 files changed, 96 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 521a71c61b16..955ca108cd4b 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -28,6 +28,7 @@ #include <drm/drm_atomic_state_helper.h> #include <drm/drm_bridge.h> +#include <drm/drm_crtc_helper.h> #include <drm/drm_debugfs.h> #include <drm/drm_edid.h> #include <drm/drm_encoder.h> @@ -879,7 +880,8 @@ static int select_bus_fmt_recursive(struct drm_bridge *first_bridge, unsigned int i, num_in_bus_fmts = 0; struct drm_bridge_state *cur_state; struct drm_bridge *prev_bridge; - u32 *in_bus_fmts; + struct drm_crtc *crtc = crtc_state->crtc; + u32 *in_bus_fmts, in_fmt; int ret; prev_bridge = drm_bridge_get_prev_bridge(cur_bridge); @@ -933,7 +935,15 @@ static int select_bus_fmt_recursive(struct drm_bridge *first_bridge, return -ENOMEM; if (first_bridge == cur_bridge) { - cur_state->input_bus_cfg.format = in_bus_fmts[0]; + in_fmt = drm_helper_crtc_select_output_bus_format(crtc, + crtc_state, + in_bus_fmts, + num_in_bus_fmts); + if (!in_fmt) { + kfree(in_bus_fmts); + return -ENOTSUPP; + } + cur_state->input_bus_cfg.format = in_fmt; cur_state->output_bus_cfg.format = out_bus_fmt; kfree(in_bus_fmts); return 0; diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c index 2dafc39a27cb..4d3aa39c8a82 100644 --- a/drivers/gpu/drm/drm_crtc_helper.c +++ b/drivers/gpu/drm/drm_crtc_helper.c @@ -1055,3 +1055,41 @@ int drm_helper_force_disable_all(struct drm_device *dev) return ret; } EXPORT_SYMBOL(drm_helper_force_disable_all); + +/** + * drm_helper_crtc_select_output_bus_format - Select output media bus format + * @crtc: The CRTC to query + * @crtc_state: The new CRTC state + * @supported_fmts: List of media bus format options to pick from + * @num_supported_fmts: Number of media bus formats in @supported_fmts list + * + * Encoder drivers may call this helper to give the connected CRTC a chance to + * select compatible or preffered media bus format to use over the CRTC encoder + * link. Encoders should provide list of supported input MEDIA_BUS_FMT_* for + * CRTC to pick from. CRTC driver is expected to select preferred media bus + * format from the list and, once enabled, generate the signal accordingly. + * + * Returns: + * Selected preferred media bus format or 0 if CRTC does not support any from + * @supported_fmts list. + */ +u32 drm_helper_crtc_select_output_bus_format(struct drm_crtc *crtc, + struct drm_crtc_state *crtc_state, + const u32 *supported_fmts, + unsigned int num_supported_fmts) +{ + if (!crtc || !crtc_state || !supported_fmts || !num_supported_fmts) + return 0; + + if (!crtc->helper_private || + !crtc->helper_private->select_output_bus_format) + crtc_state->output_bus_format = supported_fmts[0]; + else + crtc_state->output_bus_format = + crtc->helper_private->select_output_bus_format(crtc, + crtc_state, + supported_fmts, + num_supported_fmts); + return crtc_state->output_bus_format; +} +EXPORT_SYMBOL(drm_helper_crtc_select_output_bus_format); diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 8b48a1974da3..cdaa27f50af7 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -317,6 +317,17 @@ struct drm_crtc_state { */ enum drm_scaling_filter scaling_filter; + /** + * @output_bus_format: + * + * CRTC output media bus format of the video signal negotiated between + * CRTC and encoder. This value should be one of MEDIA_BUS_FMT* + * from uapi/linux/media-bus-format.h. It is safe to ignore + * @output_bus_format if CRTC doesn't support multiple output bus format + * options. + */ + u32 output_bus_format; + /** * @event: * diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h index 8c886fc46ef2..b7eb52f3ce41 100644 --- a/include/drm/drm_crtc_helper.h +++ b/include/drm/drm_crtc_helper.h @@ -38,6 +38,7 @@ struct drm_atomic_state; struct drm_connector; struct drm_crtc; +struct drm_crtc_state; struct drm_device; struct drm_display_mode; struct drm_encoder; @@ -61,5 +62,9 @@ int drm_helper_connector_dpms(struct drm_connector *connector, int mode); void drm_helper_resume_force_mode(struct drm_device *dev); int drm_helper_force_disable_all(struct drm_device *dev); +u32 drm_helper_crtc_select_output_bus_format(struct drm_crtc *crtc, + struct drm_crtc_state *crtc_state, + const u32 *supported_fmts, + unsigned int num_supported_fmts); #endif diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h index 881b03e4dc28..6d5a081e21a4 100644 --- a/include/drm/drm_modeset_helper_vtables.h +++ b/include/drm/drm_modeset_helper_vtables.h @@ -489,6 +489,36 @@ struct drm_crtc_helper_funcs { bool in_vblank_irq, int *vpos, int *hpos, ktime_t *stime, ktime_t *etime, const struct drm_display_mode *mode); + + /** + * @select_output_bus_format + * + * Called by the connected DRM encoder to negotiate input media bus + * format. CRTC is expected to pick preferable media formats from the + * list provided by the DRM encoder. + * + * This callback is optional. + * + * Parameters: + * + * crtc: + * The CRTC. + * crcs_state: + * New CRTC state. + * supported_fmts: + * List of input bus formats supported by the encoder. + * num_supported_fmts: + * Number of formats in the list. + * + * Returns: + * + * Preferred bus format from the list or 0 if CRTC doesn't support any + * from the provided list. + */ + u32 (*select_output_bus_format)(struct drm_crtc *crtc, + struct drm_crtc_state *crtc_state, + const u32 *supported_fmts, + unsigned int num_supported_fmts); }; /** -- 2.25.1