[PATCH v4 61/80] drm/omap: dsi: send nop instead of page & column

[Tomi Valkeinen]

The OMAP DSI command mode panel driver used to send page & column
address before each frame update, and this code was moved into the DSI
host driver when converting it to the DRM bridge model.

However, it's not really required to send the page & column address
before each frame. It's also something that doesn't really belong to the
DSI host driver, so we should drop the code.

That said, frame updates break if we don't send _something_ between the
frames. A NOP command does the trick.

It is not clear if this behavior is as expected from a DSI command mode
frame transfer, or is it a feature/issue with OMAP DSI driver, or a
feature/issue in the command mode panel used. So this probably needs to
be revisited later.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
---
 drivers/gpu/drm/omapdrm/dss/dsi.c | 41 +++++++++----------------------
 1 file changed, 12 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
index 7fee9cf8782d..746c2149fbbd 100644
--- a/drivers/gpu/drm/omapdrm/dss/dsi.c
+++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
@@ -3884,35 +3884,19 @@ static int _dsi_update(struct dsi_data *dsi)
 	return 0;
 }
 
-static int _dsi_update_window(struct dsi_data *dsi, int channel,
-			      int x, int y, int w, int h)
-{
-	int x1 = x, x2 = (x + w - 1);
-	int y1 = y, y2 = (y + h - 1);
-	u8 payloadX[5] = { MIPI_DCS_SET_COLUMN_ADDRESS,
-			   x1 >> 8, x1 & 0xff, x2 >> 8, x2 & 0xff };
-	u8 payloadY[5] = { MIPI_DCS_SET_PAGE_ADDRESS,
-			   y1 >> 8, y1 & 0xff, y2 >> 8, y2 & 0xff };
-	struct mipi_dsi_msg msgX = { 0 }, msgY = { 0 };
-	int ret;
+static int _dsi_send_nop(struct dsi_data *dsi, int channel)
+{
+	const u8 payload[] = { MIPI_DCS_NOP };
+	const struct mipi_dsi_msg msg = {
+		.channel = channel,
+		.type = MIPI_DSI_DCS_SHORT_WRITE,
+		.tx_len = 1,
+		.tx_buf = payload,
+	};
 
 	WARN_ON(!dsi_bus_is_locked(dsi));
 
-	msgX.type = MIPI_DSI_DCS_LONG_WRITE;
-	msgX.channel = channel;
-	msgX.tx_buf = payloadX;
-	msgX.tx_len = sizeof(payloadX);
-
-	msgY.type = MIPI_DSI_DCS_LONG_WRITE;
-	msgY.channel = channel;
-	msgY.tx_buf = payloadY;
-	msgY.tx_len = sizeof(payloadY);
-
-	ret = _omap_dsi_host_transfer(dsi, &msgX);
-	if (ret != 0)
-		return ret;
-
-	return _omap_dsi_host_transfer(dsi, &msgY);
+	return _omap_dsi_host_transfer(dsi, &msg);
 }
 
 static int dsi_update_channel(struct omap_dss_device *dssdev, int channel)
@@ -3944,10 +3928,9 @@ static int dsi_update_channel(struct omap_dss_device *dssdev, int channel)
 
 	dsi_set_ulps_auto(dsi, false);
 
-	r = _dsi_update_window(dsi, channel, 0, 0, dsi->vm.hactive,
-			       dsi->vm.vactive);
+	r = _dsi_send_nop(dsi, channel);
 	if (r < 0) {
-		DSSWARN("window update error: %d\n", r);
+		DSSWARN("failed to send nop between frames: %d\n", r);
 		goto err;
 	}
 
-- 
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