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SubjectRe: [linux-sunxi] [PATCH 3/6] drm/sun4i: dsi: Add bridge support
From
Date
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 <jagan@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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