[PATCH v3 1/1] drm/bridge: anx7625: send DPCD command to downstream

[Xin Ji <xji@xxxxxxxxxxxxxxxx>]

Send DPCD command to downstream before anx7625 power down,
let downstream monitor enter into standby mode.

Signed-off-by: Xin Ji <xji@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/bridge/analogix/anx7625.c | 42 +++++++++++++++++++----
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
index 33383f83255d..0b858c78abe8 100644
--- a/drivers/gpu/drm/bridge/analogix/anx7625.c
+++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
@@ -129,6 +129,23 @@ static int anx7625_reg_write(struct anx7625_data *ctx,
 	return ret;
 }
 
+static int anx7625_reg_block_write(struct anx7625_data *ctx,
+				   struct i2c_client *client,
+				   u8 reg_addr, u8 len, u8 *buf)
+{
+	int ret;
+	struct device *dev = &client->dev;
+
+	i2c_access_workaround(ctx, client);
+
+	ret = i2c_smbus_write_i2c_block_data(client, reg_addr, len, buf);
+	if (ret < 0)
+		dev_err(dev, "write i2c block failed id=%x\n:%x",
+			client->addr, reg_addr);
+
+	return ret;
+}
+
 static int anx7625_write_or(struct anx7625_data *ctx,
 			    struct i2c_client *client,
 			    u8 offset, u8 mask)
@@ -214,8 +231,8 @@ static int wait_aux_op_finish(struct anx7625_data *ctx)
 	return 0;
 }
 
-static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
-				 u32 address, u8 len, u8 *buf)
+static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
+				  u32 address, u8 len, u8 *buf)
 {
 	struct device *dev = &ctx->client->dev;
 	int ret;
@@ -231,8 +248,7 @@ static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
 	addrm = (address >> 8) & 0xFF;
 	addrh = (address >> 16) & 0xFF;
 
-	cmd = DPCD_CMD(len, DPCD_READ);
-	cmd = ((len - 1) << 4) | 0x09;
+	cmd = DPCD_CMD(len, op);
 
 	/* Set command and length */
 	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
@@ -246,6 +262,9 @@ static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
 	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
 				 AP_AUX_ADDR_19_16, addrh);
 
+	if (op == DPCD_WRITE)
+		ret |= anx7625_reg_block_write(ctx, ctx->i2c.rx_p0_client,
+					       AP_AUX_BUFF_START, len, buf);
 	/* Enable aux access */
 	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
 				AP_AUX_CTRL_STATUS, AP_AUX_CTRL_OP_EN);
@@ -255,14 +274,17 @@ static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
 		return -EIO;
 	}
 
-	usleep_range(2000, 2100);
-
 	ret = wait_aux_op_finish(ctx);
 	if (ret) {
 		dev_err(dev, "aux IO error: wait aux op finish.\n");
 		return ret;
 	}
 
+	/* Write done */
+	if (op == DPCD_WRITE)
+		return 0;
+
+	/* Read done, read out dpcd data */
 	ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
 				     AP_AUX_BUFF_START, len, buf);
 	if (ret < 0) {
@@ -845,7 +867,7 @@ static int anx7625_hdcp_enable(struct anx7625_data *ctx)
 	}
 
 	/* Read downstream capability */
-	anx7625_aux_dpcd_read(ctx, 0x68028, 1, &bcap);
+	anx7625_aux_dpcd_trans(ctx, DPCD_READ, 0x68028, 1, &bcap);
 	if (!(bcap & 0x01)) {
 		pr_warn("downstream not support HDCP 1.4, cap(%x).\n", bcap);
 		return 0;
@@ -918,6 +940,7 @@ static void anx7625_dp_stop(struct anx7625_data *ctx)
 {
 	struct device *dev = &ctx->client->dev;
 	int ret;
+	u8 data;
 
 	DRM_DEV_DEBUG_DRIVER(dev, "stop dp output\n");
 
@@ -929,6 +952,11 @@ static void anx7625_dp_stop(struct anx7625_data *ctx)
 	ret |= anx7625_write_and(ctx, ctx->i2c.tx_p2_client, 0x08, 0x7f);
 
 	ret |= anx7625_video_mute_control(ctx, 1);
+
+	dev_dbg(dev, "notify downstream enter into standby\n");
+	/* Downstream monitor enter into standby mode */
+	data = 2;
+	ret |= anx7625_aux_dpcd_trans(ctx, DPCD_WRITE, 0x000600, 1, &data);
 	if (ret < 0)
 		DRM_DEV_ERROR(dev, "IO error : mute video fail\n");
 
-- 
2.25.1