[PATCH] drm/ssd130x: Set the address window in ssd132x_clear_screen()

[Fabio Piparo]

ssd132x_clear_screen() sends its zeroes without setting the column and
row ranges first, so they land in whatever window the last
ssd132x_update_rect() left programmed. A partial final update then
leaves the rest of the screen uncleared, with fbcon the last damage is
typically the cursor cell, so blanking keeps the console content on
the panel.

Set the full-screen window first, as ssd130x_clear_screen() already
does.

Fixes: fdd591e00a9c ("drm/ssd130x: Add support for the SSD132x OLED controller family")
Assisted-by: LLM
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Fabio Piparo <holofermes@xxxxxxxxx>
---
Exercised on an SPI SSD1322 under local enablement patches for that
chip; compile-tested only on the SSD1325/1327. ssd133x_clear_screen()
has the same problem, left alone here for lack of hardware.

 drivers/gpu/drm/solomon/ssd130x.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 0b0fc6fe3df..256d370e240 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -900,9 +900,20 @@ static void ssd132x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
 {
 	unsigned int columns = DIV_ROUND_UP(ssd130x->width, SSD132X_SEGMENT_WIDTH);
 	unsigned int height = ssd130x->height;
+	int ret;
 
 	memset(data_array, 0, columns * height);
 
+	/* Set column start and end */
+	ret = ssd130x_write_cmd(ssd130x, 3, SSD132X_SET_COL_RANGE, 0, columns - 1);
+	if (ret < 0)
+		return;
+
+	/* Set row start and end */
+	ret = ssd130x_write_cmd(ssd130x, 3, SSD132X_SET_ROW_RANGE, 0, height - 1);
+	if (ret < 0)
+		return;
+
 	/* Write out update in one go since horizontal addressing mode is used */
 	ssd130x_write_data(ssd130x, data_array, columns * height);
 }
-- 
2.43.0