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@crapouillou.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;