The switch from devm_kzalloc() + drm_panel_init() to devm_drm_panel_alloc() introduced a regression.

Several panel descriptors do not set connector_type. For those panels, panel_simple_probe() used to compute a connector type (currently DPI as a fallback) and pass that value to drm_panel_init(). After the conversion to devm_drm_panel_alloc(), the call unconditionally used desc->connector_type instead, ignoring the computed fallback and potentially passing DRM_MODE_CONNECTOR_Unknown, which drm_panel_bridge_add() does not allow.

Move the connector_type validation / fallback logic before the devm_drm_panel_alloc() call and pass the computed connector_type to devm_drm_panel_alloc(), so panels without an explicit connector_type once again get the DPI default.

Signed-off-by: Ludovic Desroches ludovic.desroches@microchip.com Fixes: de04bb0089a9 ("drm/panel/panel-simple: Use the new allocation in place of devm_kzalloc()") Cc: stable@vger.kernel.org --- Changes in v3: - Add the tag "Cc: stable@vger.kernel.org" in the sign-off area. - Link to v2: https://lore.kernel.org/r/20251126-lcd_panel_connector_type_fix-v2-1-c15835d...

Changes in v2: - Fix a warning introduced by the code move. There is no need to jump to free_ddc, we can directly return from the function. - Link to v1: https://lore.kernel.org/r/20251121-lcd_panel_connector_type_fix-v1-1-fdbbef3... --- drivers/gpu/drm/panel/panel-simple.c | 89 ++++++++++++++++++------------------ 1 file changed, 44 insertions(+), 45 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 0019de93be1b663f55b04160606363cd043ab38b..5fd75b3939c635ca3e5b293ea37a759f479fa3f8 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -623,49 +623,6 @@ static struct panel_simple *panel_simple_probe(struct device *dev) if (IS_ERR(desc)) return ERR_CAST(desc);

- panel = devm_drm_panel_alloc(dev, struct panel_simple, base, - &panel_simple_funcs, desc->connector_type); - if (IS_ERR(panel)) - return ERR_CAST(panel); - - panel->desc = desc; - - panel->supply = devm_regulator_get(dev, "power"); - if (IS_ERR(panel->supply)) - return ERR_CAST(panel->supply); - - panel->enable_gpio = devm_gpiod_get_optional(dev, "enable", - GPIOD_OUT_LOW); - if (IS_ERR(panel->enable_gpio)) - return dev_err_cast_probe(dev, panel->enable_gpio, - "failed to request GPIO\n"); - - err = of_drm_get_panel_orientation(dev->of_node, &panel->orientation); - if (err) { - dev_err(dev, "%pOF: failed to get orientation %d\n", dev->of_node, err); - return ERR_PTR(err); - } - - ddc = of_parse_phandle(dev->of_node, "ddc-i2c-bus", 0); - if (ddc) { - panel->ddc = of_find_i2c_adapter_by_node(ddc); - of_node_put(ddc); - - if (!panel->ddc) - return ERR_PTR(-EPROBE_DEFER); - } - - if (!of_device_is_compatible(dev->of_node, "panel-dpi") && - !of_get_display_timing(dev->of_node, "panel-timing", &dt)) - panel_simple_parse_panel_timing_node(dev, panel, &dt); - - if (desc->connector_type == DRM_MODE_CONNECTOR_LVDS) { - /* Optional data-mapping property for overriding bus format */ - err = panel_simple_override_nondefault_lvds_datamapping(dev, panel); - if (err) - goto free_ddc; - } - connector_type = desc->connector_type; /* Catch common mistakes for panels. */ switch (connector_type) { @@ -690,8 +647,7 @@ static struct panel_simple *panel_simple_probe(struct device *dev) break; case DRM_MODE_CONNECTOR_eDP: dev_warn(dev, "eDP panels moved to panel-edp\n"); - err = -EINVAL; - goto free_ddc; + return ERR_PTR(-EINVAL); case DRM_MODE_CONNECTOR_DSI: if (desc->bpc != 6 && desc->bpc != 8) dev_warn(dev, "Expected bpc in {6,8} but got: %u\n", desc->bpc); @@ -720,6 +676,49 @@ static struct panel_simple *panel_simple_probe(struct device *dev) break; }

+ panel = devm_drm_panel_alloc(dev, struct panel_simple, base, + &panel_simple_funcs, connector_type); + if (IS_ERR(panel)) + return ERR_CAST(panel); + + panel->desc = desc; + + panel->supply = devm_regulator_get(dev, "power"); + if (IS_ERR(panel->supply)) + return ERR_CAST(panel->supply); + + panel->enable_gpio = devm_gpiod_get_optional(dev, "enable", + GPIOD_OUT_LOW); + if (IS_ERR(panel->enable_gpio)) + return dev_err_cast_probe(dev, panel->enable_gpio, + "failed to request GPIO\n"); + + err = of_drm_get_panel_orientation(dev->of_node, &panel->orientation); + if (err) { + dev_err(dev, "%pOF: failed to get orientation %d\n", dev->of_node, err); + return ERR_PTR(err); + } + + ddc = of_parse_phandle(dev->of_node, "ddc-i2c-bus", 0); + if (ddc) { + panel->ddc = of_find_i2c_adapter_by_node(ddc); + of_node_put(ddc); + + if (!panel->ddc) + return ERR_PTR(-EPROBE_DEFER); + } + + if (!of_device_is_compatible(dev->of_node, "panel-dpi") && + !of_get_display_timing(dev->of_node, "panel-timing", &dt)) + panel_simple_parse_panel_timing_node(dev, panel, &dt); + + if (desc->connector_type == DRM_MODE_CONNECTOR_LVDS) { + /* Optional data-mapping property for overriding bus format */ + err = panel_simple_override_nondefault_lvds_datamapping(dev, panel); + if (err) + goto free_ddc; + } + dev_set_drvdata(dev, panel);

/*

--- base-commit: ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d change-id: 20251121-lcd_panel_connector_type_fix-f00fe3766a42

Best regards,