On 06/30/2015 07:24 AM, Archit Taneja wrote:
mipi_dsi_devices are inherently aware of their host because they share a parent-child hierarchy in the device tree.
Non-dsi drivers that create a dummy dsi device don't have this data. In order to get this information, they require to a phandle to the dsi host in the device tree.
Maintain a list of all the hosts DSI that are currently registered.
This list will be used to find the mipi_dsi_host corresponding to the device_node passed in of_find_mipi_dsi_host_by_node.
The lock protects only the list, there is no guarantee that mipi_dsi_host returned by of_find_mipi_dsi_host_by_node is still valid, or will be valid long enough.
But this issue affects many kernel frameworks so I am not sure if it should block this particular patch.
Reviewed-by: Andrzej Hajda a.hajda@samsung.com
Regards Andrzej
Signed-off-by: Archit Taneja architt@codeaurora.org
drivers/gpu/drm/drm_mipi_dsi.c | 30 ++++++++++++++++++++++++++++++ include/drm/drm_mipi_dsi.h | 2 ++ 2 files changed, 32 insertions(+)
diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c index 9bfe215..81ddb73 100644 --- a/drivers/gpu/drm/drm_mipi_dsi.c +++ b/drivers/gpu/drm/drm_mipi_dsi.c @@ -239,6 +239,28 @@ struct mipi_dsi_device *mipi_dsi_new_dummy(struct mipi_dsi_host *host, u32 reg) return dsi; }
+static DEFINE_MUTEX(host_lock); +static LIST_HEAD(host_list);
+struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node) +{
- struct mipi_dsi_host *host;
- mutex_lock(&host_lock);
- list_for_each_entry(host, &host_list, list) {
if (host->dev->of_node == node) {mutex_unlock(&host_lock);return host;}- }
- mutex_unlock(&host_lock);
- return NULL;
+} +EXPORT_SYMBOL(of_find_mipi_dsi_host_by_node);
int mipi_dsi_host_register(struct mipi_dsi_host *host) { struct device_node *node; @@ -250,6 +272,10 @@ int mipi_dsi_host_register(struct mipi_dsi_host *host) of_mipi_dsi_device_add(host, node); }
- mutex_lock(&host_lock);
- list_add_tail(&host->list, &host_list);
- mutex_unlock(&host_lock);
- return 0;
} EXPORT_SYMBOL(mipi_dsi_host_register); @@ -266,6 +292,10 @@ static int mipi_dsi_remove_device_fn(struct device *dev, void *priv) void mipi_dsi_host_unregister(struct mipi_dsi_host *host) { device_for_each_child(host->dev, NULL, mipi_dsi_remove_device_fn);
- mutex_lock(&host_lock);
- list_del_init(&host->list);
- mutex_unlock(&host_lock);
} EXPORT_SYMBOL(mipi_dsi_host_unregister);
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h index d06ba99..1684a0e 100644 --- a/include/drm/drm_mipi_dsi.h +++ b/include/drm/drm_mipi_dsi.h @@ -100,10 +100,12 @@ struct mipi_dsi_host_ops { struct mipi_dsi_host { struct device *dev; const struct mipi_dsi_host_ops *ops;
- struct list_head list;
};
int mipi_dsi_host_register(struct mipi_dsi_host *host); void mipi_dsi_host_unregister(struct mipi_dsi_host *host); +struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
/* DSI mode flags */