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Message-Id: <20200216155811.68463-1-paul@crapouillou.net>
Date: Sun, 16 Feb 2020 12:58:09 -0300
From: Paul Cercueil <paul@...pouillou.net>
To: David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>
Cc: od@...c.me, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, Paul Cercueil <paul@...pouillou.net>
Subject: [PATCH 1/3] gpu/drm: ingenic: Add trick to support 16bpp on 24-bit panels
If the panel interface is 24-bit but our primary plane is 16bpp,
configure as if the panel was 18-bit. This tricks permits the display
of 16bpp data on a 24-bit panel by wiring each color component to the
MSBs of the 24-bit interface.
Signed-off-by: Paul Cercueil <paul@...pouillou.net>
---
drivers/gpu/drm/ingenic/ingenic-drm.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ingenic/ingenic-drm.c b/drivers/gpu/drm/ingenic/ingenic-drm.c
index 6d47ef7b148c..034961a40e98 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm.c
@@ -400,6 +400,8 @@ static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
struct drm_display_mode *mode = &crtc_state->adjusted_mode;
struct drm_connector *conn = conn_state->connector;
struct drm_display_info *info = &conn->display_info;
+ struct drm_plane_state *plane_state = crtc_state->crtc->primary->state;
+ const struct drm_format_info *finfo = NULL;
unsigned int cfg;
priv->panel_is_sharp = info->bus_flags & DRM_BUS_FLAG_SHARP_SIGNALS;
@@ -435,7 +437,22 @@ static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
cfg |= JZ_LCD_CFG_MODE_GENERIC_18BIT;
break;
case MEDIA_BUS_FMT_RGB888_1X24:
- cfg |= JZ_LCD_CFG_MODE_GENERIC_24BIT;
+ if (plane_state && plane_state->fb)
+ finfo = plane_state->fb->format;
+
+ /*
+ * If the panel interface is 24-bit but our
+ * primary plane is 16bpp, configure as if the
+ * panel was 18-bit. This tricks permits the
+ * display of 16bpp data on a 24-bit panel by
+ * wiring each color component to the MSBs of
+ * the 24-bit interface.
+ */
+ if (finfo &&
+ finfo->format != DRM_FORMAT_XRGB8888)
+ cfg |= JZ_LCD_CFG_MODE_GENERIC_18BIT;
+ else
+ cfg |= JZ_LCD_CFG_MODE_GENERIC_24BIT;
break;
case MEDIA_BUS_FMT_RGB888_3X8:
cfg |= JZ_LCD_CFG_MODE_8BIT_SERIAL;
--
2.25.0
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