[PATCH] drm/bridge/synopsys: dsi: fix initialization sequence

From: Yannick Fertre
Date: Fri Sep 18 2020 - 08:39:04 EST


The current driver calls drm_bridge_add(), to add the dsi bridge
to the global bridge list, in dw_mipi_dsi_host_attach().
Thus, it relies on the probing of panel or bridge sub-nodes to
trigger the execution of dsi host attach() that will, in turn,
call dw_mipi_dsi_host_attach().
This causes an incomplete driver initialization if the panel or
the next bridge is not present as sub-node, e.g. because it is an
i2c device, thus sub-node of the respective i2c controller.

Move the relevant code from host attach() to probe(), and the
corresponding code from detach() to remove().

Signed-off-by: Antonio Borneo <antonio.borneo@xxxxxx>
Signed-off-by: Yannick Fertre <yannick.fertre@xxxxxx>
---
drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 73 ++++++++++++-------
1 file changed, 48 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index 6b268f9445b3..aa74abddc79f 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
@@ -314,9 +314,7 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host,
{
struct dw_mipi_dsi *dsi = host_to_dsi(host);
const struct dw_mipi_dsi_plat_data *pdata = dsi->plat_data;
- struct drm_bridge *bridge;
- struct drm_panel *panel;
- int ret;
+ int ret = -ENODEV;

if (device->lanes > dsi->plat_data->max_data_lanes) {
dev_err(dsi->dev, "the number of data lanes(%u) is too many\n",
@@ -329,22 +327,6 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host,
dsi->format = device->format;
dsi->mode_flags = device->mode_flags;

- ret = drm_of_find_panel_or_bridge(host->dev->of_node, 1, 0,
- &panel, &bridge);
- if (ret)
- return ret;
-
- if (panel) {
- bridge = drm_panel_bridge_add_typed(panel,
- DRM_MODE_CONNECTOR_DSI);
- if (IS_ERR(bridge))
- return PTR_ERR(bridge);
- }
-
- dsi->panel_bridge = bridge;
-
- drm_bridge_add(&dsi->bridge);
-
if (pdata->host_ops && pdata->host_ops->attach) {
ret = pdata->host_ops->attach(pdata->priv_data, device);
if (ret < 0)
@@ -367,10 +349,6 @@ static int dw_mipi_dsi_host_detach(struct mipi_dsi_host *host,
return ret;
}

- drm_of_panel_bridge_remove(host->dev->of_node, 1, 0);
-
- drm_bridge_remove(&dsi->bridge);
-
return 0;
}

@@ -1105,6 +1083,9 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
struct device *dev = &pdev->dev;
struct reset_control *apb_rst;
struct dw_mipi_dsi *dsi;
+ struct drm_bridge *bridge;
+ struct drm_panel *panel;
+ int i, nb_endpoints;
int ret;

dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
@@ -1172,8 +1153,7 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
ret = mipi_dsi_host_register(&dsi->dsi_host);
if (ret) {
dev_err(dev, "Failed to register MIPI host: %d\n", ret);
- dw_mipi_dsi_debugfs_remove(dsi);
- return ERR_PTR(ret);
+ goto err_pmr_enable;
}

dsi->bridge.driver_private = dsi;
@@ -1182,11 +1162,54 @@ __dw_mipi_dsi_probe(struct platform_device *pdev,
dsi->bridge.of_node = pdev->dev.of_node;
#endif

+ /* Get number of endpoints */
+ nb_endpoints = of_graph_get_endpoint_count(pdev->dev.of_node);
+ if (!nb_endpoints) {
+ ret = -ENODEV;
+ goto err_host_reg;
+ }
+
+ for (i = 1; i < nb_endpoints; i++) {
+ ret = drm_of_find_panel_or_bridge(pdev->dev.of_node, i, 0,
+ &panel, &bridge);
+ if (!ret)
+ break;
+ else if (ret == -EPROBE_DEFER)
+ goto err_host_reg;
+ }
+
+ /* check if an error is returned >> no panel or bridge detected */
+ if (ret)
+ goto err_host_reg;
+
+ if (panel) {
+ bridge = drm_panel_bridge_add_typed(panel, DRM_MODE_CONNECTOR_DSI);
+ if (IS_ERR(bridge)) {
+ ret = PTR_ERR(bridge);
+ goto err_host_reg;
+ }
+ }
+
+ dsi->panel_bridge = bridge;
+
+ drm_bridge_add(&dsi->bridge);
+
return dsi;
+
+err_host_reg:
+ mipi_dsi_host_unregister(&dsi->dsi_host);
+
+err_pmr_enable:
+ pm_runtime_disable(dev);
+ dw_mipi_dsi_debugfs_remove(dsi);
+
+ return ERR_PTR(ret);
}

static void __dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi)
{
+ drm_bridge_remove(&dsi->bridge);
+ drm_panel_bridge_remove(dsi->panel_bridge);
mipi_dsi_host_unregister(&dsi->dsi_host);

pm_runtime_disable(dsi->dev);
--
2.17.1