[PATCH 2/3] drm/ssd130x: fix ssd132x encoding

From: John Keeping
Date: Mon Jan 13 2025 - 10:28:42 EST


The ssd132x buffer is encoded one pixel per nibble, with two pixels in
each byte. When encoding and 8-bit greyscale input, take the top 4-bits
as the value and ensure the two pixels are distinct and do not overwrite
each other.

Signed-off-by: John Keeping <jkeeping@xxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/solomon/ssd130x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 2622172228361..64f1123080996 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -880,7 +880,7 @@ static int ssd132x_update_rect(struct ssd130x_device *ssd130x,
u8 n1 = buf[i * width + j];
u8 n2 = buf[i * width + j + 1];

- data_array[array_idx++] = (n2 << 4) | n1;
+ data_array[array_idx++] = (n2 & 0xf0) | (n1 >> 4);
}
}

--
2.47.1