diff options
| -rw-r--r-- | drivers/gpu/drm/drm_bridge.c | 267 | ||||
| -rw-r--r-- | include/drm/drm_bridge.h | 124 |
2 files changed, 390 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 8e4b799150b0..37400607e9b7 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -672,12 +672,260 @@ static int drm_atomic_bridge_check(struct drm_bridge *bridge, } /** + * drm_atomic_helper_bridge_propagate_bus_fmt() - Propagate output format to + * the input end of a bridge + * @bridge: bridge control structure + * @bridge_state: new bridge state + * @crtc_state: new CRTC state + * @conn_state: new connector state + * @output_fmt: tested output bus format + * @num_input_fmts: will contain the size of the returned array + * + * This helper is a pluggable implementation of the + * &drm_bridge_funcs.atomic_get_input_bus_fmts operation for bridges that don't + * modify the bus configuration between their input and their output. It + * returns an array of input formats with a single element set to @output_fmt. + * + * RETURNS: + * a valid format array of size @num_input_fmts, or NULL if the allocation + * failed + */ +u32 * +drm_atomic_helper_bridge_propagate_bus_fmt(struct drm_bridge *bridge, + struct drm_bridge_state *bridge_state, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state, + u32 output_fmt, + unsigned int *num_input_fmts) +{ + u32 *input_fmts; + + input_fmts = kzalloc(sizeof(*input_fmts), GFP_KERNEL); + if (!input_fmts) { + *num_input_fmts = 0; + return NULL; + } + + *num_input_fmts = 1; + input_fmts[0] = output_fmt; + return input_fmts; +} +EXPORT_SYMBOL(drm_atomic_helper_bridge_propagate_bus_fmt); + +static int select_bus_fmt_recursive(struct drm_bridge *first_bridge, + struct drm_bridge *cur_bridge, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state, + u32 out_bus_fmt) +{ + struct drm_bridge_state *cur_state; + unsigned int num_in_bus_fmts, i; + struct drm_bridge *prev_bridge; + u32 *in_bus_fmts; + int ret; + + prev_bridge = drm_bridge_get_prev_bridge(cur_bridge); + cur_state = drm_atomic_get_new_bridge_state(crtc_state->state, + cur_bridge); + if (WARN_ON(!cur_state)) + return -EINVAL; + + /* + * If bus format negotiation is not supported by this bridge, let's + * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and + * hope that it can handle this situation gracefully (by providing + * appropriate default values). + */ + if (!cur_bridge->funcs->atomic_get_input_bus_fmts) { + if (cur_bridge != first_bridge) { + ret = select_bus_fmt_recursive(first_bridge, + prev_bridge, crtc_state, + conn_state, + MEDIA_BUS_FMT_FIXED); + if (ret) + return ret; + } + + cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED; + cur_state->output_bus_cfg.format = out_bus_fmt; + return 0; + } + + in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge, + cur_state, + crtc_state, + conn_state, + out_bus_fmt, + &num_in_bus_fmts); + if (!num_in_bus_fmts) + return -ENOTSUPP; + else if (!in_bus_fmts) + return -ENOMEM; + + if (first_bridge == cur_bridge) { + cur_state->input_bus_cfg.format = in_bus_fmts[0]; + cur_state->output_bus_cfg.format = out_bus_fmt; + kfree(in_bus_fmts); + return 0; + } + + for (i = 0; i < num_in_bus_fmts; i++) { + ret = select_bus_fmt_recursive(first_bridge, prev_bridge, + crtc_state, conn_state, + in_bus_fmts[i]); + if (ret != -ENOTSUPP) + break; + } + + if (!ret) { + cur_state->input_bus_cfg.format = in_bus_fmts[i]; + cur_state->output_bus_cfg.format = out_bus_fmt; + } + + kfree(in_bus_fmts); + return ret; +} + +/* + * This function is called by &drm_atomic_bridge_chain_check() just before + * calling &drm_bridge_funcs.atomic_check() on all elements of the chain. + * It performs bus format negotiation between bridge elements. The negotiation + * happens in reverse order, starting from the last element in the chain up to + * @bridge. + * + * Negotiation starts by retrieving supported output bus formats on the last + * bridge element and testing them one by one. The test is recursive, meaning + * that for each tested output format, the whole chain will be walked backward, + * and each element will have to choose an input bus format that can be + * transcoded to the requested output format. When a bridge element does not + * support transcoding into a specific output format -ENOTSUPP is returned and + * the next bridge element will have to try a different format. If none of the + * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail. + * + * This implementation is relying on + * &drm_bridge_funcs.atomic_get_output_bus_fmts() and + * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported + * input/output formats. + * + * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by + * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts() + * tries a single format: &drm_connector.display_info.bus_formats[0] if + * available, MEDIA_BUS_FMT_FIXED otherwise. + * + * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented, + * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the + * bridge element that lacks this hook and asks the previous element in the + * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what + * to do in that case (fail if they want to enforce bus format negotiation, or + * provide a reasonable default if they need to support pipelines where not + * all elements support bus format negotiation). + */ +static int +drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state) +{ + struct drm_connector *conn = conn_state->connector; + struct drm_encoder *encoder = bridge->encoder; + struct drm_bridge_state *last_bridge_state; + unsigned int i, num_out_bus_fmts; + struct drm_bridge *last_bridge; + u32 *out_bus_fmts; + int ret = 0; + + last_bridge = list_last_entry(&encoder->bridge_chain, + struct drm_bridge, chain_node); + last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state, + last_bridge); + if (WARN_ON(!last_bridge_state)) + return -EINVAL; + + if (last_bridge->funcs->atomic_get_output_bus_fmts) { + const struct drm_bridge_funcs *funcs = last_bridge->funcs; + + out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge, + last_bridge_state, + crtc_state, + conn_state, + &num_out_bus_fmts); + if (!num_out_bus_fmts) + return -ENOTSUPP; + else if (!out_bus_fmts) + return -ENOMEM; + } else { + num_out_bus_fmts = 1; + out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL); + if (!out_bus_fmts) + return -ENOMEM; + + if (conn->display_info.num_bus_formats && + conn->display_info.bus_formats) + out_bus_fmts[0] = conn->display_info.bus_formats[0]; + else + out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED; + } + + for (i = 0; i < num_out_bus_fmts; i++) { + ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state, + conn_state, out_bus_fmts[i]); + if (ret != -ENOTSUPP) + break; + } + + kfree(out_bus_fmts); + + return ret; +} + +static void +drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge, + struct drm_connector *conn, + struct drm_atomic_state *state) +{ + struct drm_bridge_state *bridge_state, *next_bridge_state; + struct drm_bridge *next_bridge; + u32 output_flags; + + bridge_state = drm_atomic_get_new_bridge_state(state, bridge); + next_bridge = drm_bridge_get_next_bridge(bridge); + + /* + * Let's try to apply the most common case here, that is, propagate + * display_info flags for the last bridge, and propagate the input + * flags of the next bridge element to the output end of the current + * bridge when the bridge is not the last one. + * There are exceptions to this rule, like when signal inversion is + * happening at the board level, but that's something drivers can deal + * with from their &drm_bridge_funcs.atomic_check() implementation by + * simply overriding the flags value we've set here. + */ + if (!next_bridge) { + output_flags = conn->display_info.bus_flags; + } else { + next_bridge_state = drm_atomic_get_new_bridge_state(state, + next_bridge); + output_flags = next_bridge_state->input_bus_cfg.flags; + } + + bridge_state->output_bus_cfg.flags = output_flags; + + /* + * Propage the output flags to the input end of the bridge. Again, it's + * not necessarily what all bridges want, but that's what most of them + * do, and by doing that by default we avoid forcing drivers to + * duplicate the "dummy propagation" logic. + */ + bridge_state->input_bus_cfg.flags = output_flags; +} + +/** * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain * @bridge: bridge control structure * @crtc_state: new CRTC state * @conn_state: new connector state * - * Calls &drm_bridge_funcs.atomic_check() (falls back on + * First trigger a bus format negotiation before calling + * &drm_bridge_funcs.atomic_check() (falls back on * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain, * starting from the last bridge to the first. These are called before calling * &drm_encoder_helper_funcs.atomic_check() @@ -689,12 +937,29 @@ int drm_atomic_bridge_chain_check(struct drm_bridge *bridge, struct drm_crtc_state *crtc_state, struct drm_connector_state *conn_state) { + struct drm_connector *conn = conn_state->connector; struct drm_encoder *encoder = bridge->encoder; struct drm_bridge *iter; + int ret; + + ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state, + conn_state); + if (ret) + return ret; list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) { int ret; + /* + * Bus flags are propagated by default. If a bridge needs to + * tweak the input bus flags for any reason, it should happen + * in its &drm_bridge_funcs.atomic_check() implementation such + * that preceding bridges in the chain can propagate the new + * bus flags. + */ + drm_atomic_bridge_propagate_bus_flags(iter, conn, + crtc_state->state); + ret = drm_atomic_bridge_check(iter, crtc_state, conn_state); if (ret) return ret; diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index ae0595c70132..46e15526b087 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -36,6 +36,38 @@ struct drm_bridge_timings; struct drm_panel; /** + * struct drm_bus_cfg - bus configuration + * + * This structure stores the configuration of a physical bus between two + * components in an output pipeline, usually between two bridges, an encoder + * and a bridge, or a bridge and a connector. + * + * The bus configuration is stored in &drm_bridge_state separately for the + * input and output buses, as seen from the point of view of each bridge. The + * bus configuration of a bridge output is usually identical to the + * configuration of the next bridge's input, but may differ if the signals are + * modified between the two bridges, for instance by an inverter on the board. + * The input and output configurations of a bridge may differ if the bridge + * modifies the signals internally, for instance by performing format + * conversion, or modifying signals polarities. + */ +struct drm_bus_cfg { + /** + * @format: format used on this bus (one of the MEDIA_BUS_FMT_* format) + * + * This field should not be directly modified by drivers + * (&drm_atomic_bridge_chain_select_bus_fmts() takes care of the bus + * format negotiation). + */ + u32 format; + + /** + * @flags: DRM_BUS_* flags used on this bus + */ + u32 flags; +}; + +/** * struct drm_bridge_state - Atomic bridge state object * @base: inherit from &drm_private_state * @bridge: the bridge this state refers to @@ -44,6 +76,16 @@ struct drm_bridge_state { struct drm_private_state base; struct drm_bridge *bridge; + + /** + * @input_bus_cfg: input bus configuration + */ + struct drm_bus_cfg input_bus_cfg; + + /** + * @output_bus_cfg: input bus configuration + */ + struct drm_bus_cfg output_bus_cfg; }; static inline struct drm_bridge_state * @@ -388,6 +430,72 @@ struct drm_bridge_funcs { struct drm_bridge_state *state); /** + * @atomic_get_output_bus_fmts: + * + * Return the supported bus formats on the output end of a bridge. + * The returned array must be allocated with kmalloc() and will be + * freed by the caller. If the allocation fails, NULL should be + * returned. num_output_fmts must be set to the returned array size. + * Formats listed in the returned array should be listed in decreasing + * preference order (the core will try all formats until it finds one + * that works). + * + * This method is only called on the last element of the bridge chain + * as part of the bus format negotiation process that happens in + * &drm_atomic_bridge_chain_select_bus_fmts(). + * This method is optional. When not implemented, the core will + * fall back to &drm_connector.display_info.bus_formats[0] if + * &drm_connector.display_info.num_bus_formats > 0, + * or to MEDIA_BUS_FMT_FIXED otherwise. + */ + u32 *(*atomic_get_output_bus_fmts)(struct drm_bridge *bridge, + struct drm_bridge_state *bridge_state, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state, + unsigned int *num_output_fmts); + + /** + * @atomic_get_input_bus_fmts: + * + * Return the supported bus formats on the input end of a bridge for + * a specific output bus format. + * + * The returned array must be allocated with kmalloc() and will be + * freed by the caller. If the allocation fails, NULL should be + * returned. num_output_fmts must be set to the returned array size. + * Formats listed in the returned array should be listed in decreasing + * preference order (the core will try all formats until it finds one + * that works). When the format is not supported NULL should be + * returned and *num_output_fmts should be set to 0. + * + * This method is called on all elements of the bridge chain as part of + * the bus format negotiation process that happens in + * &drm_atomic_bridge_chain_select_bus_fmts(). + * This method is optional. When not implemented, the core will bypass + * bus format negotiation on this element of the bridge without + * failing, and the previous element in the chain will be passed + * MEDIA_BUS_FMT_FIXED as its output bus format. + * + * Bridge drivers that need to support being linked to bridges that are + * not supporting bus format negotiation should handle the + * output_fmt == MEDIA_BUS_FMT_FIXED case appropriately, by selecting a + * sensible default value or extracting this information from somewhere + * else (FW property, &drm_display_mode, &drm_display_info, ...) + * + * Note: Even if input format selection on the first bridge has no + * impact on the negotiation process (bus format negotiation stops once + * we reach the first element of the chain), drivers are expected to + * return accurate input formats as the input format may be used to + * configure the CRTC output appropriately. + */ + u32 *(*atomic_get_input_bus_fmts)(struct drm_bridge *bridge, + struct drm_bridge_state *bridge_state, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state, + u32 output_fmt, + unsigned int *num_input_fmts); + + /** * @atomic_check: * * This method is responsible for checking bridge state correctness. @@ -401,6 +509,14 @@ struct drm_bridge_funcs { * called when &drm_bridge_funcs.atomic_check() is implemented, so only * one of them should be provided. * + * If drivers need to tweak &drm_bridge_state.input_bus_cfg.flags or + * &drm_bridge_state.output_bus_cfg.flags it should should happen in + * this function. By default the &drm_bridge_state.output_bus_cfg.flags + * field is set to the next bridge + * &drm_bridge_state.input_bus_cfg.flags value or + * &drm_connector.display_info.bus_flags if the bridge is the last + * element in the chain. + * * RETURNS: * zero if the check passed, a negative error code otherwise. */ @@ -588,6 +704,14 @@ void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge, void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge, struct drm_atomic_state *state); +u32 * +drm_atomic_helper_bridge_propagate_bus_fmt(struct drm_bridge *bridge, + struct drm_bridge_state *bridge_state, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state, + u32 output_fmt, + unsigned int *num_input_fmts); + void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge, struct drm_bridge_state *state); void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge, |