drm/bridge: adv7533: Change number of DSI lanes dynamically

Lower modes on ADV7533 require lower number of DSI lanes for correct
operation. If ADV7533 is being used with 4 DSI lanes, then switch the
lanes to 3 when the target mode's pixel clock is less than 80 Mhz.

Based on patch by Andy Green <andy.green@linaro.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>

drivers/gpu/drm/bridge/adv7511/adv7511.h

@@ -339,6 +339,7 @@ struct adv7511 {
 #ifdef CONFIG_DRM_I2C_ADV7533
 void adv7533_dsi_power_on(struct adv7511 *adv);
 void adv7533_dsi_power_off(struct adv7511 *adv);
+void adv7533_mode_set(struct adv7511 *adv, struct drm_display_mode *mode);
 int adv7533_patch_registers(struct adv7511 *adv);
 void adv7533_uninit_cec(struct adv7511 *adv);
 int adv7533_init_cec(struct adv7511 *adv);
@@ -354,6 +355,11 @@ static inline void adv7533_dsi_power_off(struct adv7511 *adv)
 {
 }
 
+static inline void adv7533_mode_set(struct adv7511 *adv,
+				    struct drm_display_mode *mode)
+{
+}
+
 static inline int adv7533_patch_registers(struct adv7511 *adv)
 {
 	return -ENODEV;

drivers/gpu/drm/bridge/adv7511/adv7511_drv.c

@@ -712,6 +712,9 @@ static void adv7511_mode_set(struct adv7511 *adv7511,
 	regmap_update_bits(adv7511->regmap, 0x17,
 		0x60, (vsync_polarity << 6) | (hsync_polarity << 5));
 
+	if (adv7511->type == ADV7533)
+		adv7533_mode_set(adv7511, adj_mode);
+
 	drm_mode_copy(&adv7511->curr_mode, adj_mode);
 
 	/*

drivers/gpu/drm/bridge/adv7511/adv7533.c

@@ -115,6 +115,28 @@ void adv7533_dsi_power_off(struct adv7511 *adv)
 	regmap_write(adv->regmap_cec, 0x27, 0x0b);
 }
 
+void adv7533_mode_set(struct adv7511 *adv, struct drm_display_mode *mode)
+{
+	struct mipi_dsi_device *dsi = adv->dsi;
+	int lanes, ret;
+
+	if (adv->num_dsi_lanes != 4)
+		return;
+
+	if (mode->clock > 80000)
+		lanes = 4;
+	else
+		lanes = 3;
+
+	if (lanes != dsi->lanes) {
+		mipi_dsi_detach(dsi);
+		dsi->lanes = lanes;
+		ret = mipi_dsi_attach(dsi);
+		if (ret)
+			dev_err(&dsi->dev, "failed to change host lanes\n");
+	}
+}
+
 int adv7533_patch_registers(struct adv7511 *adv)
 {
 	return regmap_register_patch(adv->regmap,