Add OF notifier handler needed for creating/destroying MIPI DSI devices according to dynamic runtime changes in the DT live tree. This code is enabled when CONFIG_OF_DYNAMIC is selected.
This is based on existing code for I2C and SPI subsystems. Signed-off-by: Chen-Yu Tsai <we...@chromium.org> --- This is a patch I wrote for the ChromeOS SKU component prober [1]. That series is still being worked on, but in the meantime I thought this patch might be useful to Luca. Luca talked about a hot-pluggable connector that has DSI at ELC earlier this year. If DT live tree patching is used in this case, this patch could be needed. [1] https://lore.kernel.org/linux-arm-kernel/20231109100606.1245545-1-we...@chromium.org/ drivers/gpu/drm/drm_mipi_dsi.c | 67 +++++++++++++++++++++++++++++++++- 1 file changed, 66 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c index a471c46f5ca6..a47e8928db53 100644 --- a/drivers/gpu/drm/drm_mipi_dsi.c +++ b/drivers/gpu/drm/drm_mipi_dsi.c @@ -118,6 +118,7 @@ static void mipi_dsi_dev_release(struct device *dev) { struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev); + of_node_clear_flag(dev->of_node, OF_POPULATED); of_node_put(dev->of_node); kfree(dsi); } @@ -158,6 +159,7 @@ static struct mipi_dsi_device * of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node) { struct mipi_dsi_device_info info = { }; + struct mipi_dsi_device *device; int ret; u32 reg; @@ -175,9 +177,70 @@ of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node) info.channel = reg; info.node = of_node_get(node); + of_node_set_flag(node, OF_POPULATED); - return mipi_dsi_device_register_full(host, &info); + device = mipi_dsi_device_register_full(host, &info); + if (IS_ERR(device)) + of_node_clear_flag(node, OF_POPULATED); + + return device; } + +#if IS_ENABLED(CONFIG_OF_DYNAMIC) +static int of_mipi_dsi_notify(struct notifier_block *nb, unsigned long action, void *arg) +{ + struct of_reconfig_data *rd = arg; + struct mipi_dsi_host *host; + struct mipi_dsi_device *device; + + switch (of_reconfig_get_state_change(action, rd)) { + case OF_RECONFIG_CHANGE_ADD: + host = of_find_mipi_dsi_host_by_node(rd->dn->parent); + if (!host) + return NOTIFY_OK; /* not for us */ + + if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) + return NOTIFY_OK; + + /* + * Clear the flag before adding the device so that fw_devlink + * doesn't skip adding consumers to this device. + */ + rd->dn->fwnode.flags &= ~FWNODE_FLAG_NOT_DEVICE; + device = of_mipi_dsi_device_add(host, rd->dn); + if (IS_ERR(device)) { + dev_err(host->dev, "failed to create device for '%pOF'\n", rd->dn); + of_node_clear_flag(rd->dn, OF_POPULATED); + return notifier_from_errno(PTR_ERR(device)); + } + break; + case OF_RECONFIG_CHANGE_REMOVE: + /* already depopulated? */ + if (!of_node_check_flag(rd->dn, OF_POPULATED)) + return NOTIFY_OK; + + /* find our device by node */ + device = of_find_mipi_dsi_device_by_node(rd->dn); + if (!device) + return NOTIFY_OK; /* no? not meant for us */ + + /* unregister takes one ref away */ + mipi_dsi_device_unregister(device); + + /* and put the reference of the find */ + put_device(&device->dev); + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block mipi_dsi_of_notifier = { + .notifier_call = of_mipi_dsi_notify, +}; +#else +static struct notifier_block mipi_dsi_of_notifier __always_unused; +#endif #else static struct mipi_dsi_device * of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node) @@ -1703,6 +1766,8 @@ EXPORT_SYMBOL(mipi_dsi_driver_unregister); static int __init mipi_dsi_bus_init(void) { + if (IS_ENABLED(CONFIG_OF_DYNAMIC)) + WARN_ON(of_reconfig_notifier_register(&mipi_dsi_of_notifier)); return bus_register(&mipi_dsi_bus_type); } postcore_initcall(mipi_dsi_bus_init); -- 2.45.2.741.gdbec12cfda-goog
