linux-kernel - [PATCH v2 4/6] drm/st7571-i2c: add support for inverted pixel format

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Message-Id: <20250721-st7571-format-v2-4-159f4134098c@gmail.com>
Date: Mon, 21 Jul 2025 12:43:34 +0200
From: Marcus Folkesson <marcus.folkesson@...il.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Javier Martinez Canillas <javierm@...hat.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, Marcus Folkesson <marcus.folkesson@...il.com>
Subject: [PATCH v2 4/6] drm/st7571-i2c: add support for inverted pixel
 format

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.

Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
 drivers/gpu/drm/sitronix/st7571-i2c.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
index dfdd0fa4ff24090c3cbe7ab162285be45464d6a6..9f2de057ce9d990fdd77e395a6c32ba1e2f36137 100644
--- a/drivers/gpu/drm/sitronix/st7571-i2c.c
+++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
@@ -151,6 +151,7 @@ struct st7571_device {
 	bool ignore_nak;
 
 	bool grayscale;
+	bool inverted;
 	u32 height_mm;
 	u32 width_mm;
 	u32 startline;
@@ -792,6 +793,7 @@ static int st7567_parse_dt(struct st7571_device *st7567)
 
 	of_property_read_u32(np, "width-mm", &st7567->width_mm);
 	of_property_read_u32(np, "height-mm", &st7567->height_mm);
+	st7567->inverted = of_property_read_bool(np, "sitronix,inverted");
 
 	st7567->pformat = &st7571_monochrome;
 	st7567->bpp = 1;
@@ -819,6 +821,7 @@ 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;
@@ -873,7 +876,7 @@ static int st7567_lcd_init(struct st7571_device *st7567)
 		ST7571_SET_POWER(0x6),	/* Power Control, VC: ON, VR: ON, VF: OFF */
 		ST7571_SET_POWER(0x7),	/* Power Control, VC: ON, VR: ON, VF: ON */
 
-		ST7571_SET_REVERSE(0),
+		ST7571_SET_REVERSE(st7567->inverted ? 1 : 0),
 		ST7571_SET_ENTIRE_DISPLAY_ON(0),
 	};
 
@@ -917,7 +920,7 @@ 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