Hi,

On Fri, 2019-03-15 at 18:38 +0530, Jagan Teki wrote:
> Some display panels would come up with a non-DSI output which
> can have an option to connect DSI interface by means of bridge
> convertor.
> 
> This DSI to non-DSI bridge convertor would require a bridge
> driver that would communicate the DSI controller for bridge
> functionalities.
> 
> So, add support for bridge functionalities in Allwinner DSI
> controller.

See a few comments below.

> Signed-off-by: Jagan Teki <ja...@amarulasolutions.com>
> ---
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 65 +++++++++++++++++++-------
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h |  1 +
>  2 files changed, 49 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c 
> b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 0960b96b62cc..64d74313b842 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -781,6 +781,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder 
> *encoder)
>       if (!IS_ERR(dsi->panel))
>               drm_panel_prepare(dsi->panel);
>  
> +     if (!IS_ERR(dsi->bridge))
> +             drm_bridge_pre_enable(dsi->bridge);
> +
>       /*
>        * FIXME: This should be moved after the switch to HS mode.
>        *
> @@ -796,6 +799,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder 
> *encoder)
>       if (!IS_ERR(dsi->panel))
>               drm_panel_enable(dsi->panel);
>  
> +     if (!IS_ERR(dsi->bridge))
> +             drm_bridge_enable(dsi->bridge);
> +
>       sun6i_dsi_start(dsi, DSI_START_HSC);
>  
>       udelay(1000);
> @@ -812,6 +818,9 @@ static void sun6i_dsi_encoder_disable(struct drm_encoder 
> *encoder)
>       if (!IS_ERR(dsi->panel)) {
>               drm_panel_disable(dsi->panel);
>               drm_panel_unprepare(dsi->panel);
> +     } else if (!IS_ERR(dsi->bridge)) {
> +             drm_bridge_disable(dsi->bridge);
> +             drm_bridge_post_disable(dsi->bridge);
>       }
>  
>       phy_power_off(dsi->dphy);
> @@ -973,11 +982,16 @@ static int sun6i_dsi_attach(struct mipi_dsi_host *host,
>       struct sun6i_dsi *dsi = host_to_sun6i_dsi(host);
>  
>       dsi->device = device;
> -     dsi->panel = of_drm_find_panel(device->dev.of_node);
> -     if (IS_ERR(dsi->panel))
> -             return PTR_ERR(dsi->panel);
>  
> -     dev_info(host->dev, "Attached device %s\n", device->name);
> +     dsi->bridge = of_drm_find_bridge(device->dev.of_node);
> +     if (!dsi->bridge) {

You are using IS_ERR to check that the bridge is alive in the changes
above, but switch to checking that it's non-NULL at this point.

Are both guaranteed to be interchangeable?

> +             dsi->panel = of_drm_find_panel(device->dev.of_node);
> +             if (IS_ERR(dsi->panel))
> +                     return PTR_ERR(dsi->panel);
> +     }

You should probably use drm_of_find_panel_or_bridge instead of
duplicating the logic here.

> +     dev_info(host->dev, "Attached %s %s\n",
> +              dsi->bridge ? "bridge" : "panel", device->name);
>  
>       return 0;
>  }
> @@ -1055,8 +1069,10 @@ static int sun6i_dsi_bind(struct device *dev, struct 
> device *master,
>       struct sun4i_tcon *tcon0 = sun4i_get_tcon0(drm);
>       int ret;
>  
> -     if (!dsi->panel)
> +     if (!(dsi->panel || dsi->bridge)) {
> +             dev_info(drm->dev, "No panel or bridge found... DSI output 
> disabled\n");
>               return -EPROBE_DEFER;
> +     }
>  
>       dsi->drv = drv;
>  
> @@ -1078,19 +1094,29 @@ static int sun6i_dsi_bind(struct device *dev, struct 
> device *master,
>       }
>       dsi->encoder.possible_crtcs = BIT(0);
>  
> -     drm_connector_helper_add(&dsi->connector,
> -                              &sun6i_dsi_connector_helper_funcs);
> -     ret = drm_connector_init(drm, &dsi->connector,
> -                              &sun6i_dsi_connector_funcs,
> -                              DRM_MODE_CONNECTOR_DSI);
> -     if (ret) {
> -             dev_err(dsi->dev,
> -                     "Couldn't initialise the DSI connector\n");
> -             goto err_cleanup_connector;
> +     if (dsi->panel) {
> +             drm_connector_helper_add(&dsi->connector,
> +                                      &sun6i_dsi_connector_helper_funcs);
> +             ret = drm_connector_init(drm, &dsi->connector,
> +                                      &sun6i_dsi_connector_funcs,
> +                                      DRM_MODE_CONNECTOR_DSI);
> +             if (ret) {
> +                     dev_err(dsi->dev,
> +                             "Couldn't initialise the DSI connector\n");
> +                     goto err_cleanup_connector;
> +             }
> +
> +             drm_connector_attach_encoder(&dsi->connector, &dsi->encoder);
> +             drm_panel_attach(dsi->panel, &dsi->connector);
>       }
>  
> -     drm_connector_attach_encoder(&dsi->connector, &dsi->encoder);
> -     drm_panel_attach(dsi->panel, &dsi->connector);
> +     if (dsi->bridge) {
> +             ret = drm_bridge_attach(&dsi->encoder, dsi->bridge, NULL);
> +             if (ret) {
> +                     dev_err(dsi->dev, "Couldn't attach the DSI bridge\n");
> +                     goto err_cleanup_connector;
> +             }
> +     }
>  
>       return 0;
>  
> @@ -1104,7 +1130,12 @@ static void sun6i_dsi_unbind(struct device *dev, 
> struct device *master,
>  {
>       struct sun6i_dsi *dsi = dev_get_drvdata(dev);
>  
> -     drm_panel_detach(dsi->panel);
> +     if (dsi->panel)
> +             drm_panel_detach(dsi->panel);
> +
> +     if (dsi->bridge)
> +             drm_bridge_detach(dsi->bridge);

As I mentionned in the first patch, this is quite suspicious since the
DRM core should be in charge of detaching the bridge, not the driver.

Cheers,

Paul

> +
>  }
>  
>  static const struct component_ops sun6i_dsi_ops = {
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h 
> b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
> index 5c4983212f89..76874ff8e3ef 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
> @@ -36,6 +36,7 @@ struct sun6i_dsi {
>       struct sun4i_tcon       *tcon;
>       struct mipi_dsi_device  *device;
>       struct drm_panel        *panel;
> +     struct drm_bridge       *bridge;
>       const struct sun6i_dsi_variant  *variant;
>  };
>  
> -- 
> 2.18.0.321.gffc6fa0e3
> 
-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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