[PATCH v2 3/5] drm/mipi_dbi: Add support for display offsets

[Geert Uytterhoeven]

If the resolution of the TFT display is smaller than the maximum
resolution supported by the display controller, the display may be
connected to the driver output arrays with a horizontal and/or vertical
offset, leading to a shifted image.

Add support for specifying these offsets.

Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
Reviewed-by: Sam Ravnborg <sam at ravnborg.org>
---
v2:
  - Add Reviewed-by.
---
 drivers/gpu/drm/drm_mipi_dbi.c | 30 ++++++++++++++++++++----------
 include/drm/drm_mipi_dbi.h     | 12 ++++++++++++
 2 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index 16bff1be4b8ac622..27fe81a53c88e338 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -238,6 +238,23 @@ int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
 }
 EXPORT_SYMBOL(mipi_dbi_buf_copy);
 
+static void mipi_dbi_set_window_address(struct mipi_dbi_dev *dbidev,
+					unsigned int xs, unsigned int xe,
+					unsigned int ys, unsigned int ye)
+{
+	struct mipi_dbi *dbi = &dbidev->dbi;
+
+	xs += dbidev->left_offset;
+	xe += dbidev->left_offset;
+	ys += dbidev->top_offset;
+	ye += dbidev->top_offset;
+
+	mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS, (xs >> 8) & 0xff,
+			 xs & 0xff, (xe >> 8) & 0xff, xe & 0xff);
+	mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS, (ys >> 8) & 0xff,
+			 ys & 0xff, (ye >> 8) & 0xff, ye & 0xff);
+}
+
 static void mipi_dbi_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect)
 {
 	struct drm_gem_object *gem = drm_gem_fb_get_obj(fb, 0);
@@ -271,12 +288,8 @@ static void mipi_dbi_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect)
 		tr = cma_obj->vaddr;
 	}
 
-	mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS,
-			 (rect->x1 >> 8) & 0xff, rect->x1 & 0xff,
-			 ((rect->x2 - 1) >> 8) & 0xff, (rect->x2 - 1) & 0xff);
-	mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS,
-			 (rect->y1 >> 8) & 0xff, rect->y1 & 0xff,
-			 ((rect->y2 - 1) >> 8) & 0xff, (rect->y2 - 1) & 0xff);
+	mipi_dbi_set_window_address(dbidev, rect->x1, rect->x2 - 1, rect->y1,
+				    rect->y2 - 1);
 
 	ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START, tr,
 				   width * height * 2);
@@ -366,10 +379,7 @@ static void mipi_dbi_blank(struct mipi_dbi_dev *dbidev)
 
 	memset(dbidev->tx_buf, 0, len);
 
-	mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS, 0, 0,
-			 ((width - 1) >> 8) & 0xFF, (width - 1) & 0xFF);
-	mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS, 0, 0,
-			 ((height - 1) >> 8) & 0xFF, (height - 1) & 0xFF);
+	mipi_dbi_set_window_address(dbidev, 0, width - 1, 0, height - 1);
 	mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START,
 			     (u8 *)dbidev->tx_buf, len);
 
diff --git a/include/drm/drm_mipi_dbi.h b/include/drm/drm_mipi_dbi.h
index 67c66f5ee591e80f..33f325f5af2b921f 100644
--- a/include/drm/drm_mipi_dbi.h
+++ b/include/drm/drm_mipi_dbi.h
@@ -109,6 +109,18 @@ struct mipi_dbi_dev {
 	 */
 	unsigned int rotation;
 
+	/**
+	 * @left_offset: Horizontal offset of the display relative to the
+	 *               controller's driver array
+	 */
+	unsigned int left_offset;
+
+	/**
+	 * @top_offset: Vertical offset of the display relative to the
+	 *              controller's driver array
+	 */
+	unsigned int top_offset;
+
 	/**
 	 * @backlight: backlight device (optional)
 	 */
-- 
2.17.1