drm/apple: Only assume RGB planes on internal displays are sRGB

For external displays with EDID user space might use the colorimetry
information therein and use color mapping with the expectation of using
that color space. DCP's native color space is the correct choice for
that.

Fixes: 667ca85 ("drm: apple: Assume all RGB planes are sRGB")
Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/gpu/drm/apple/iomfb_template.c

@@ -1362,6 +1362,14 @@ void DCP_FW_NAME(iomfb_flush)(struct apple_dcp *dcp, struct drm_crtc *crtc, stru
 		req->surf_iova[l] = apple_state->iova;
 		req->surf[l].base = apple_state->surf;
 
+		/* Use sRGB colorspace only for internal panels. External
+		 * displays are expected to have EDID and user space can use
+		 * the contained colorimetry information to provide native
+		 * colors.
+		 */
+		if (dcp->connector_type == DRM_MODE_CONNECTOR_eDP &&
+		    req->surf[l].base.colorspace == DCP_COLORSPACE_BG_SRGB)
+			req->surf[l].base.colorspace = DCP_COLORSPACE_NATIVE;
 	}
 
 	if (!has_surface && !crtc_state->color_mgmt_changed) {

drivers/gpu/drm/apple/plane.c

@@ -191,7 +191,7 @@ static enum dcp_colorspace get_colorspace(bool is_yuv,
 					  enum drm_color_encoding enc)
 {
 	if (!is_yuv)
-		return DCP_COLORSPACE_BG_SRGB;
+		return DCP_COLORSPACE_NATIVE;
 
 	switch (enc) {
 	case DRM_COLOR_YCBCR_BT601: