From e5248ffbc4ed2a8ccc6c3944a9a654226e303791 Mon Sep 17 00:00:00 2001
From: Julien STEPHAN <jstephan@baylibre.com>
Date: Mon, 14 Feb 2022 10:27:42 +0100
Subject: drm/mediatek: Allow commands to be sent during video mode
Git-commit: 81cc7e51c4f1686b71e30046437056ece6b2cb4d
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

Mipi dsi panel drivers can use mipi_dsi_dcs_{set,get}_display_brightness()
to request backlight changes.

This can be done during panel initialization (dsi is in command mode)
or afterwards (dsi is in Video Mode).

When the DSI is in Video Mode, all commands are rejected.

Detect current DSI mode in mtk_dsi_host_transfer() and switch modes
temporarily to allow commands to be sent.

Signed-off-by: Julien STEPHAN <jstephan@baylibre.com>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 33 ++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index bced4c7d668e..ccb0511b9cd5 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -974,24 +974,33 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 	u8 read_data[16];
 	void *src_addr;
 	u8 irq_flag = CMD_DONE_INT_FLAG;
+	u32 dsi_mode;
+	int ret;
 
-	if (readl(dsi->regs + DSI_MODE_CTRL) & MODE) {
-		DRM_ERROR("dsi engine is not command mode\n");
-		return -EINVAL;
+	dsi_mode = readl(dsi->regs + DSI_MODE_CTRL);
+	if (dsi_mode & MODE) {
+		mtk_dsi_stop(dsi);
+		ret = mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
+		if (ret)
+			goto restore_dsi_mode;
 	}
 
 	if (MTK_DSI_HOST_IS_READ(msg->type))
 		irq_flag |= LPRX_RD_RDY_INT_FLAG;
 
-	if (mtk_dsi_host_send_cmd(dsi, msg, irq_flag) < 0)
-		return -ETIME;
+	ret = mtk_dsi_host_send_cmd(dsi, msg, irq_flag);
+	if (ret)
+		goto restore_dsi_mode;
 
-	if (!MTK_DSI_HOST_IS_READ(msg->type))
-		return 0;
+	if (!MTK_DSI_HOST_IS_READ(msg->type)) {
+		recv_cnt = 0;
+		goto restore_dsi_mode;
+	}
 
 	if (!msg->rx_buf) {
 		DRM_ERROR("dsi receive buffer size may be NULL\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto restore_dsi_mode;
 	}
 
 	for (i = 0; i < 16; i++)
@@ -1016,7 +1025,13 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 	DRM_INFO("dsi get %d byte data from the panel address(0x%x)\n",
 		 recv_cnt, *((u8 *)(msg->tx_buf)));
 
-	return recv_cnt;
+restore_dsi_mode:
+	if (dsi_mode & MODE) {
+		mtk_dsi_set_mode(dsi);
+		mtk_dsi_start(dsi);
+	}
+
+	return ret < 0 ? ret : recv_cnt;
 }
 
 static const struct mipi_dsi_host_ops mtk_dsi_ops = {
-- 
2.38.1