drm/bridge: display-connector: implement bus fmts callbacks

commit 7cd70656d1285b79c001f041a017fcfee4292ff9 upstream.

Since this bridge is tied to the connector, it acts like a passthrough,
so concerning the output & input bus formats, either pass the bus formats from the
previous bridge or return fallback data like done in the bridge function:
drm_atomic_bridge_chain_select_bus_fmts() & select_bus_fmt_recursive.

This permits avoiding skipping the negociation if the remaining bridge chain has
all the bits in place.

Without this bus fmt negociation breaks on drm/meson HDMI pipeline when attaching
dw-hdmi with DRM_BRIDGE_ATTACH_NO_CONNECTOR, because the last bridge of the
display-connector doesn't implement buf fmt callbacks and MEDIA_BUS_FMT_FIXED
is used leading to select an unsupported default bus format from dw-hdmi.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020123947.2585572-2-narmstrong@baylibre.com
Cc: Stefan Agner <stefan@agner.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/bridge/display-connector.c b/drivers/gpu/drm/bridge/display-connector.c
index 847a0dce7f1d3faad3a3d18f76ab643d12f5d6c3..d24f5b90feabfbeff13472e741b08a366cd25f91 100644 (file)
--- a/drivers/gpu/drm/bridge/display-connector.c
+++ b/drivers/gpu/drm/bridge/display-connector.c
@@ -13,6 +13,7 @@
 #include <linux/platform_device.h>
 #include <linux/regulator/consumer.h>
 
+#include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_edid.h>
 
@@ -87,10 +88,95 @@ static struct edid *display_connector_get_edid(struct drm_bridge *bridge,
        return drm_get_edid(connector, conn->bridge.ddc);
 }
 
+/*
+ * Since this bridge is tied to the connector, it acts like a passthrough,
+ * so concerning the output bus formats, either pass the bus formats from the
+ * previous bridge or return fallback data like done in the bridge function:
+ * drm_atomic_bridge_chain_select_bus_fmts().
+ * This supports negotiation if the bridge chain has all bits in place.
+ */
+static u32 *display_connector_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)
+{
+       struct drm_bridge *prev_bridge = drm_bridge_get_prev_bridge(bridge);
+       struct drm_bridge_state *prev_bridge_state;
+
+       if (!prev_bridge || !prev_bridge->funcs->atomic_get_output_bus_fmts) {
+               struct drm_connector *conn = conn_state->connector;
+               u32 *out_bus_fmts;
+
+               *num_output_fmts = 1;
+               out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
+               if (!out_bus_fmts)
+                       return NULL;
+
+               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;
+
+               return out_bus_fmts;
+       }
+
+       prev_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
+                                                           prev_bridge);
+
+       return prev_bridge->funcs->atomic_get_output_bus_fmts(prev_bridge, prev_bridge_state,
+                                                             crtc_state, conn_state,
+                                                             num_output_fmts);
+}
+
+/*
+ * Since this bridge is tied to the connector, it acts like a passthrough,
+ * so concerning the input bus formats, either pass the bus formats from the
+ * previous bridge or MEDIA_BUS_FMT_FIXED (like select_bus_fmt_recursive())
+ * when atomic_get_input_bus_fmts is not supported.
+ * This supports negotiation if the bridge chain has all bits in place.
+ */
+static u32 *display_connector_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)
+{
+       struct drm_bridge *prev_bridge = drm_bridge_get_prev_bridge(bridge);
+       struct drm_bridge_state *prev_bridge_state;
+
+       if (!prev_bridge || !prev_bridge->funcs->atomic_get_input_bus_fmts) {
+               u32 *in_bus_fmts;
+
+               *num_input_fmts = 1;
+               in_bus_fmts = kmalloc(sizeof(*in_bus_fmts), GFP_KERNEL);
+               if (!in_bus_fmts)
+                       return NULL;
+
+               in_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
+
+               return in_bus_fmts;
+       }
+
+       prev_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
+                                                           prev_bridge);
+
+       return prev_bridge->funcs->atomic_get_input_bus_fmts(prev_bridge, prev_bridge_state,
+                                                            crtc_state, conn_state, output_fmt,
+                                                            num_input_fmts);
+}
+
 static const struct drm_bridge_funcs display_connector_bridge_funcs = {
        .attach = display_connector_attach,
        .detect = display_connector_detect,
        .get_edid = display_connector_get_edid,
+       .atomic_get_output_bus_fmts = display_connector_get_output_bus_fmts,
+       .atomic_get_input_bus_fmts = display_connector_get_input_bus_fmts,
+       .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
+       .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+       .atomic_reset = drm_atomic_helper_bridge_reset,
 };
 
 static irqreturn_t display_connector_hpd_irq(int irq, void *arg)