drm/bridge: cdns-dsi: Move DSI mode check to _atomic_check()

At present, the DSI mode configuration check happens during the
_atomic_enable() phase, which is not really the best place for this.
Moreover, if the mode is not valid, the driver gives a warning and
continues the hardware configuration.

Move the DSI mode configuration check to _atomic_check() instead, which
can properly report back any invalid mode, before the _enable phase even
begins.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
Signed-off-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Link: https://lore.kernel.org/r/20250329113925.68204-10-aradhya.bhatia@linux.dev
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c

@@ -425,6 +425,17 @@
 #define DSI_NULL_FRAME_OVERHEAD		6
 #define DSI_EOT_PKT_SIZE		4
 
+struct cdns_dsi_bridge_state {
+	struct drm_bridge_state base;
+	struct cdns_dsi_cfg dsi_cfg;
+};
+
+static inline struct cdns_dsi_bridge_state *
+to_cdns_dsi_bridge_state(struct drm_bridge_state *bridge_state)
+{
+	return container_of(bridge_state, struct cdns_dsi_bridge_state, base);
+}
+
 static inline struct cdns_dsi *input_to_dsi(struct cdns_dsi_input *input)
 {
 	return container_of(input, struct cdns_dsi, input);
@@ -771,6 +782,8 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
 	struct cdns_dsi_output *output = &dsi->output;
 	struct drm_connector_state *conn_state;
 	struct drm_crtc_state *crtc_state;
+	struct cdns_dsi_bridge_state *dsi_state;
+	struct drm_bridge_state *new_bridge_state;
 	struct drm_display_mode *mode;
 	struct phy_configure_opts_mipi_dphy *phy_cfg = &output->phy_opts.mipi_dphy;
 	struct drm_connector *connector;
@@ -782,6 +795,13 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
 	if (WARN_ON(pm_runtime_get_sync(dsi->base.dev) < 0))
 		return;
 
+	new_bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
+	if (WARN_ON(!new_bridge_state))
+		return;
+
+	dsi_state = to_cdns_dsi_bridge_state(new_bridge_state);
+	dsi_cfg = dsi_state->dsi_cfg;
+
 	if (dsi->platform_ops && dsi->platform_ops->enable)
 		dsi->platform_ops->enable(dsi);
 
@@ -791,8 +811,6 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
 	mode = &crtc_state->adjusted_mode;
 	nlanes = output->dev->lanes;
 
-	WARN_ON_ONCE(cdns_dsi_check_conf(dsi, mode, &dsi_cfg, false));
-
 	cdns_dsi_hs_init(dsi);
 	cdns_dsi_init_link(dsi);
 
@@ -963,6 +981,70 @@ static u32 *cdns_dsi_bridge_get_input_bus_fmts(struct drm_bridge *bridge,
 	return input_fmts;
 }
 
+static int cdns_dsi_bridge_atomic_check(struct drm_bridge *bridge,
+					struct drm_bridge_state *bridge_state,
+					struct drm_crtc_state *crtc_state,
+					struct drm_connector_state *conn_state)
+{
+	struct cdns_dsi_input *input = bridge_to_cdns_dsi_input(bridge);
+	struct cdns_dsi *dsi = input_to_dsi(input);
+	struct cdns_dsi_bridge_state *dsi_state = to_cdns_dsi_bridge_state(bridge_state);
+	const struct drm_display_mode *mode = &crtc_state->mode;
+	struct cdns_dsi_cfg *dsi_cfg = &dsi_state->dsi_cfg;
+
+	return cdns_dsi_check_conf(dsi, mode, dsi_cfg, false);
+}
+
+static struct drm_bridge_state *
+cdns_dsi_bridge_atomic_duplicate_state(struct drm_bridge *bridge)
+{
+	struct cdns_dsi_bridge_state *dsi_state, *old_dsi_state;
+	struct drm_bridge_state *bridge_state;
+
+	if (WARN_ON(!bridge->base.state))
+		return NULL;
+
+	bridge_state = drm_priv_to_bridge_state(bridge->base.state);
+	old_dsi_state = to_cdns_dsi_bridge_state(bridge_state);
+
+	dsi_state = kzalloc(sizeof(*dsi_state), GFP_KERNEL);
+	if (!dsi_state)
+		return NULL;
+
+	__drm_atomic_helper_bridge_duplicate_state(bridge, &dsi_state->base);
+
+	memcpy(&dsi_state->dsi_cfg, &old_dsi_state->dsi_cfg,
+	       sizeof(dsi_state->dsi_cfg));
+
+	return &dsi_state->base;
+}
+
+static void
+cdns_dsi_bridge_atomic_destroy_state(struct drm_bridge *bridge,
+				     struct drm_bridge_state *state)
+{
+	struct cdns_dsi_bridge_state *dsi_state;
+
+	dsi_state = to_cdns_dsi_bridge_state(state);
+
+	kfree(dsi_state);
+}
+
+static struct drm_bridge_state *
+cdns_dsi_bridge_atomic_reset(struct drm_bridge *bridge)
+{
+	struct cdns_dsi_bridge_state *dsi_state;
+
+	dsi_state = kzalloc(sizeof(*dsi_state), GFP_KERNEL);
+	if (!dsi_state)
+		return NULL;
+
+	memset(dsi_state, 0, sizeof(*dsi_state));
+	dsi_state->base.bridge = bridge;
+
+	return &dsi_state->base;
+}
+
 static const struct drm_bridge_funcs cdns_dsi_bridge_funcs = {
 	.attach = cdns_dsi_bridge_attach,
 	.mode_valid = cdns_dsi_bridge_mode_valid,
@@ -970,9 +1052,10 @@ static const struct drm_bridge_funcs cdns_dsi_bridge_funcs = {
 	.atomic_pre_enable = cdns_dsi_bridge_atomic_pre_enable,
 	.atomic_enable = cdns_dsi_bridge_atomic_enable,
 	.atomic_post_disable = cdns_dsi_bridge_atomic_post_disable,
-	.atomic_reset = drm_atomic_helper_bridge_reset,
-	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
-	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+	.atomic_check = cdns_dsi_bridge_atomic_check,
+	.atomic_reset = cdns_dsi_bridge_atomic_reset,
+	.atomic_duplicate_state = cdns_dsi_bridge_atomic_duplicate_state,
+	.atomic_destroy_state = cdns_dsi_bridge_atomic_destroy_state,
 	.atomic_get_input_bus_fmts = cdns_dsi_bridge_get_input_bus_fmts,
 };