Hi Dmitry,
Thank you for the patch.
On Fri, Apr 17, 2020 at 08:52:38PM +0300, Dmitry Osipenko wrote:
> 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.
>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> 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..f28a226914c0 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.
As I tried to explain before, if you wrap the panel in a bridge with
drm_panel_bridge_add() (or the devm_ variant), you will always have a
bridge associated with the output, and will be able to remove your
custom connector implementation. I thus recommend converting to
drm_panel_bridge_add() either as part of this patch series, or just
after it, to get full benefits.
With the assumption that this will be handled,
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> + */
> + 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) {
--
Regards,
Laurent Pinchart
