drm/vc4: dpi: Change the default DPI format to being 18bpp, not 24.

DPI hasn't really been used up until now, so the default has
been meaningless.
In theory we should be able to pass the desired format for the
adjacent bridge chip through, but framework seems to be missing
for that.

As the main device to use DPI is the VGA666 or Adafruit Kippah,
both of which use RGB666, change the default to being RGB666 instead
of RGB888.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20221013-rpi-dpi-improvements-v3-6-eb76e26a772d@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c
index ecbe4cd870365095125f658667703ac2cdeb8f82..fdae02760b6df754229c0b41b5d882a4ddf23358 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_dpi.c
+++ b/drivers/gpu/drm/vc4/vc4_dpi.c
@@ -150,8 +150,8 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
        }
        drm_connector_list_iter_end(&conn_iter);
 
-       /* Default to 24bit if no connector or format found. */
-       dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB, DPI_FORMAT);
+       /* Default to 18bit if no connector or format found. */
+       dpi_c |= VC4_SET_FIELD(DPI_FORMAT_18BIT_666_RGB_1, DPI_FORMAT);
 
        if (connector) {
                if (connector->display_info.num_bus_formats) {