drm/mipi_dbi: Add support for display offsets

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@glider.be>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200115124548.3951-4-geert+renesas@glider.be

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 16bff1be4b8a..27fe81a53c88 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 67c66f5ee591..33f325f5af2b 100644
--- a/include/drm/drm_mipi_dbi.h
+++ b/include/drm/drm_mipi_dbi.h
@@ -110,6 +110,18 @@ 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)
 	 */
 	struct backlight_device *backlight;