[PATCH 3/5] drm/st7571-i2c: add support inverted pixel format

[Marcus Folkesson]

Depending on which display that is connected to the controller, an
"1" means either a black or a white pixel.

The supported formats (R1/R2/XRGB8888) expects the pixels
to map against (4bit):
    00 => Black
    01 => Dark Gray
    10 => Light Gray
    11 => White

If this is not what the display map against, make it possible to invert
the pixels.

Signed-off-by: Marcus Folkesson <marcus.folkes...@gmail.com>
---
 drivers/gpu/drm/sitronix/st7571-i2c.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c 
b/drivers/gpu/drm/sitronix/st7571-i2c.c
index 
3024c94c890497d1ddbbf0f7f81ec4664f48d580..6a5d719f8b0044ec700ff119972b580c904ffb27
 100644
--- a/drivers/gpu/drm/sitronix/st7571-i2c.c
+++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
@@ -147,6 +147,7 @@ struct st7571_device {
        bool ignore_nak;
 
        bool grayscale;
+       bool inverted;
        u32 height_mm;
        u32 width_mm;
        u32 startline;
@@ -789,6 +790,7 @@ static int st7571_parse_dt(struct st7571_device *st7571)
        of_property_read_u32(np, "width-mm", &st7571->width_mm);
        of_property_read_u32(np, "height-mm", &st7571->height_mm);
        st7571->grayscale = of_property_read_bool(np, "sitronix,grayscale");
+       st7571->inverted = of_property_read_bool(np, "sitronix,inverted");
 
        if (st7571->grayscale) {
                st7571->pformat = &st7571_grayscale;
@@ -853,7 +855,7 @@ static int st7571_lcd_init(struct st7571_device *st7571)
                ST7571_SET_COLOR_MODE(st7571->pformat->mode),
                ST7571_COMMAND_SET_NORMAL,
 
-               ST7571_SET_REVERSE(0),
+               ST7571_SET_REVERSE(st7571->inverted ? 1 : 0),
                ST7571_SET_ENTIRE_DISPLAY_ON(0),
        };
 

-- 
2.49.0