drm/bridge/synopsys: dw-hdmi: don't clobber drvdata

dw_hdmi shouldn't set drvdata since some drivers might need to store
it's own data there. Rework dw_hdmi in a way to return struct dw_hdmi
instead to store it in drvdata. This way drivers are responsible to
store and pass structure when needed.

Idea was taken from the following commit:
8242ecbd59 ("drm/bridge/synopsys: stop clobbering drvdata")

Cc: p.zabel@pengutronix.de
Cc: Laurent.pinchart@ideasonboard.com
Cc: hjc@rock-chips.com
Acked-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180214200906.31509-6-jernej.skrabec@siol.net

drivers/gpu/drm/meson/meson_dw_hdmi.c

@@ -140,6 +140,7 @@ struct meson_dw_hdmi {
 	struct clk *venci_clk;
 	struct regulator *hdmi_supply;
 	u32 irq_stat;
+	struct dw_hdmi *hdmi;
 };
 #define encoder_to_meson_dw_hdmi(x) \
 	container_of(x, struct meson_dw_hdmi, encoder)
@@ -878,9 +879,12 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 	dw_plat_data->input_bus_format = MEDIA_BUS_FMT_YUV8_1X24;
 	dw_plat_data->input_bus_encoding = V4L2_YCBCR_ENC_709;
 
-	ret = dw_hdmi_bind(pdev, encoder, &meson_dw_hdmi->dw_plat_data);
-	if (ret)
-		return ret;
+	platform_set_drvdata(pdev, meson_dw_hdmi);
+
+	meson_dw_hdmi->hdmi = dw_hdmi_bind(pdev, encoder,
+					   &meson_dw_hdmi->dw_plat_data);
+	if (IS_ERR(meson_dw_hdmi->hdmi))
+		return PTR_ERR(meson_dw_hdmi->hdmi);
 
 	DRM_DEBUG_DRIVER("HDMI controller initialized\n");
 
@@ -890,7 +894,9 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 static void meson_dw_hdmi_unbind(struct device *dev, struct device *master,
 				   void *data)
 {
-	dw_hdmi_unbind(dev);
+	struct meson_dw_hdmi *meson_dw_hdmi = dev_get_drvdata(dev);
+
+	dw_hdmi_unbind(meson_dw_hdmi->hdmi);
 }
 
 static const struct component_ops meson_dw_hdmi_ops = {