[PATCH v2] drm/mediatek: allow commands to be sent during video mode

[Julien STEPHAN <jstephan@xxxxxxxxxxxx>]

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@xxxxxxxxxxxx>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@xxxxxxxxxxxx>
---
Changes in v2:
  - update commit message to be more descriptive

 drivers/gpu/drm/mediatek/mtk_dsi.c | 34 ++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 5d90d2eb0019..7d66fdc7f81d 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -891,24 +891,34 @@ 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;
-
-	if (readl(dsi->regs + DSI_MODE_CTRL) & MODE) {
-		DRM_ERROR("dsi engine is not command mode\n");
-		return -EINVAL;
+	u32 dsi_mode;
+
+	dsi_mode = readl(dsi->regs + DSI_MODE_CTRL);
+	if (dsi_mode & MODE) {
+		mtk_dsi_stop(dsi);
+		if (mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500)) {
+			recv_cnt = -EINVAL;
+			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;
+	if (mtk_dsi_host_send_cmd(dsi, msg, irq_flag) < 0) {
+		recv_cnt = -ETIME;
+		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;
+		recv_cnt = -EINVAL;
+		goto restore_dsi_mode;
 	}
 
 	for (i = 0; i < 16; i++)
@@ -933,6 +943,12 @@ 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)));
 
+restore_dsi_mode:
+	if (dsi_mode & MODE) {
+		mtk_dsi_set_mode(dsi);
+		mtk_dsi_start(dsi);
+	}
+
 	return recv_cnt;
 }
 
-- 
2.35.1