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    Subject[PATCH v8 5/7] drm/tegra: output: rgb: Support LVDS encoder bridge
    Date
    Newer Tegra device-trees will specify a video output graph, which involves
    LVDS encoder bridge. This patch adds support for the LVDS encoder bridge
    to the RGB output, allowing us to model the display hardware properly.

    Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
    Acked-by: Sam Ravnborg <sam@ravnborg.org>
    Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
    ---
    drivers/gpu/drm/tegra/rgb.c | 58 +++++++++++++++++++++++++++++++------
    1 file changed, 49 insertions(+), 9 deletions(-)

    diff --git a/drivers/gpu/drm/tegra/rgb.c b/drivers/gpu/drm/tegra/rgb.c
    index 0562a7eb793f..9a7024ec96bc 100644
    --- a/drivers/gpu/drm/tegra/rgb.c
    +++ b/drivers/gpu/drm/tegra/rgb.c
    @@ -7,6 +7,7 @@
    #include <linux/clk.h>

    #include <drm/drm_atomic_helper.h>
    +#include <drm/drm_bridge_connector.h>
    #include <drm/drm_panel.h>
    #include <drm/drm_simple_kms_helper.h>

    @@ -267,24 +268,63 @@ int tegra_dc_rgb_remove(struct tegra_dc *dc)
    int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
    {
    struct tegra_output *output = dc->rgb;
    + struct drm_connector *connector;
    int err;

    if (!dc->rgb)
    return -ENODEV;

    - drm_connector_init(drm, &output->connector, &tegra_rgb_connector_funcs,
    - DRM_MODE_CONNECTOR_LVDS);
    - drm_connector_helper_add(&output->connector,
    - &tegra_rgb_connector_helper_funcs);
    - output->connector.dpms = DRM_MODE_DPMS_OFF;
    -
    drm_simple_encoder_init(drm, &output->encoder, DRM_MODE_ENCODER_LVDS);
    drm_encoder_helper_add(&output->encoder,
    &tegra_rgb_encoder_helper_funcs);

    - drm_connector_attach_encoder(&output->connector,
    - &output->encoder);
    - drm_connector_register(&output->connector);
    + /*
    + * Tegra devices that have LVDS panel utilize LVDS encoder bridge
    + * for converting up to 28 LCD LVTTL lanes into 5/4 LVDS lanes that
    + * go to display panel's receiver.
    + *
    + * Encoder usually have a power-down control which needs to be enabled
    + * in order to transmit data to the panel. Historically devices that
    + * use an older device-tree version didn't model the bridge, assuming
    + * that encoder is turned ON by default, while today's DRM allows us
    + * to model LVDS encoder properly.
    + *
    + * Newer device-trees utilize LVDS encoder bridge, which provides
    + * us with a connector and handles the display panel.
    + *
    + * For older device-trees we fall back to our own connector and use
    + * nvidia,panel phandle.
    + */
    + if (output->bridge) {
    + err = drm_bridge_attach(&output->encoder, output->bridge,
    + NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
    + if (err) {
    + dev_err(output->dev, "failed to attach bridge: %d\n",
    + err);
    + return err;
    + }
    +
    + connector = drm_bridge_connector_init(drm, &output->encoder);
    + if (IS_ERR(connector)) {
    + dev_err(output->dev,
    + "failed to initialize bridge connector: %pe\n",
    + connector);
    + return PTR_ERR(connector);
    + }
    +
    + drm_connector_attach_encoder(connector, &output->encoder);
    + } else {
    + drm_connector_init(drm, &output->connector,
    + &tegra_rgb_connector_funcs,
    + DRM_MODE_CONNECTOR_LVDS);
    + drm_connector_helper_add(&output->connector,
    + &tegra_rgb_connector_helper_funcs);
    + output->connector.dpms = DRM_MODE_DPMS_OFF;
    +
    + drm_connector_attach_encoder(&output->connector,
    + &output->encoder);
    + drm_connector_register(&output->connector);
    + }

    err = tegra_output_init(drm, output);
    if (err < 0) {
    --
    2.26.0
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