drm/bridge: nwl-dsi: Get MIPI DSI controller and PHY ready in ->mode_set()

Some MIPI DSI panel drivers like 'raydium,rm68200' send
MIPI_DCS_SET_DISPLAY_ON commands in panel_funcs->prepare(), which
requires the MIPI DSI controller and PHY to be ready beforehand.
Without this patch, the nwl-dsi driver gets the MIPI DSI controller
and PHY ready in bridge_funcs->atomic_pre_enable(), which happens after
the panel_funcs->prepare().  So, this patch shifts the bridge operation
ealier from bridge_funcs->atomic_pre_enable() to bridge_funcs->mode_set().
This way, more MIPI DSI panels can connect to this nwl-dsi bridge.

Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Guido Günther <agx@sigxcpu.org>
Cc: Robert Chiras <robert.chiras@nxp.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1619170003-4817-4-git-send-email-victor.liu@nxp.com

drivers/gpu/drm/bridge/nwl-dsi.c

@@ -662,7 +662,7 @@ static irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-static int nwl_dsi_enable(struct nwl_dsi *dsi)
+static int nwl_dsi_mode_set(struct nwl_dsi *dsi)
 {
 	struct device *dev = dsi->dev;
 	union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
@@ -834,7 +834,12 @@ static int nwl_dsi_bridge_atomic_check(struct drm_bridge *bridge,
 	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
 	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
 
-	/* Do a full modeset if crtc_state->active is changed to be true. */
+	/*
+	 * Do a full modeset if crtc_state->active is changed to be true.
+	 * This ensures our ->mode_set() is called to get the DSI controller
+	 * and the PHY ready to send DCS commands, when only the connector's
+	 * DPMS is brought out of "Off" status.
+	 */
 	if (crtc_state->active_changed && crtc_state->active)
 		crtc_state->mode_changed = true;
 
@@ -863,16 +868,8 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
 
 	memcpy(&dsi->mode, adjusted_mode, sizeof(dsi->mode));
 	drm_mode_debug_printmodeline(adjusted_mode);
-}
-
-static void
-nwl_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
-				 struct drm_bridge_state *old_bridge_state)
-{
-	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
-	int ret;
 
-	pm_runtime_get_sync(dsi->dev);
+	pm_runtime_get_sync(dev);
 
 	if (clk_prepare_enable(dsi->lcdif_clk) < 0)
 		return;
@@ -882,22 +879,22 @@ nwl_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
 	/* Step 1 from DSI reset-out instructions */
 	ret = reset_control_deassert(dsi->rst_pclk);
 	if (ret < 0) {
-		DRM_DEV_ERROR(dsi->dev, "Failed to deassert PCLK: %d\n", ret);
+		DRM_DEV_ERROR(dev, "Failed to deassert PCLK: %d\n", ret);
 		return;
 	}
 
 	/* Step 2 from DSI reset-out instructions */
-	nwl_dsi_enable(dsi);
+	nwl_dsi_mode_set(dsi);
 
 	/* Step 3 from DSI reset-out instructions */
 	ret = reset_control_deassert(dsi->rst_esc);
 	if (ret < 0) {
-		DRM_DEV_ERROR(dsi->dev, "Failed to deassert ESC: %d\n", ret);
+		DRM_DEV_ERROR(dev, "Failed to deassert ESC: %d\n", ret);
 		return;
 	}
 	ret = reset_control_deassert(dsi->rst_byte);
 	if (ret < 0) {
-		DRM_DEV_ERROR(dsi->dev, "Failed to deassert BYTE: %d\n", ret);
+		DRM_DEV_ERROR(dev, "Failed to deassert BYTE: %d\n", ret);
 		return;
 	}
 }
@@ -953,7 +950,6 @@ static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
 	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
 	.atomic_reset		= drm_atomic_helper_bridge_reset,
 	.atomic_check		= nwl_dsi_bridge_atomic_check,
-	.atomic_pre_enable	= nwl_dsi_bridge_atomic_pre_enable,
 	.atomic_enable		= nwl_dsi_bridge_atomic_enable,
 	.atomic_disable		= nwl_dsi_bridge_atomic_disable,
 	.mode_set		= nwl_dsi_bridge_mode_set,