[PATCH v2 6/8] drm/dsi: add helper function to find the second host in a dual-dsi setup

Heiko Stuebner
2018-06-18T10:28:04Z

From a specified output port of one dsi controller this function allows to
iterate over the list of registered dsi controllers trying to find a second
instance connected to the same display, like it is used in dual-dsi setups.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
drivers/gpu/drm/drm_mipi_dsi.c | 56 ++++++++++++++++++++++++++++++++++
include/drm/drm_mipi_dsi.h | 2 ++
2 files changed, 58 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index bc73b7f5b9fc..0c3c9c7aa3b8 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -30,6 +30,7 @@
#include <linux/device.h>
#include <linux/module.h>
#include <linux/of_device.h>
+#include <linux/of_graph.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>

@@ -282,6 +283,61 @@ struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node)
}
EXPORT_SYMBOL(of_find_mipi_dsi_host_by_node);

+struct device_node *of_mipi_dsi_find_second_host(struct device_node *first_np,
+ int port, int endpoint)
+{
+ struct mipi_dsi_host *first, *host;
+ struct device_node *remote, *np, *second_np = NULL;
+ int num = 0;
+
+ first = of_find_mipi_dsi_host_by_node(first_np);
+ if (!first) {
+ pr_err("no dsi-host for node %s\n", first_np->full_name);
+ return ERR_PTR(-ENODEV);
+ }
+
+ /* output-node of the known dsi-host */
+ remote = of_graph_get_remote_node(first_np, port, endpoint);
+ if (!remote) {
+ dev_err(first->dev, "no output node found\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ mutex_lock(&host_lock);
+
+ list_for_each_entry(host, &host_list, list) {
+ np = of_graph_get_remote_node(host->dev->of_node,
+ port, endpoint);
+
+ /* found a host connected to this panel */
+ if (np == remote)
+ num++;
+
+ /* found one second host */
+ if (host->dev->of_node != first_np)
+ second_np = host->dev->of_node;
+
+ of_node_put(np);
+ }
+
+ /* of_node_get the node under host_lock */
+ if (num == 2)
+ of_node_get(second_np);
+
+ mutex_unlock(&host_lock);
+
+ of_node_put(remote);
+
+ if (num > 2) {
+ dev_err(first->dev,
+ "too many DSI links for output: %d links\n", num);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return second_np;
+}
+EXPORT_SYMBOL(of_mipi_dsi_find_second_host);
+
int mipi_dsi_host_register(struct mipi_dsi_host *host)
{
struct device_node *node;
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 4fef19064b0f..89532ae69c91 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -107,6 +107,8 @@ struct mipi_dsi_host {
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);
+struct device_node *of_mipi_dsi_find_second_host(struct device_node *first_np,
+ int port, int endpoint);

/* DSI mode flags */

--
2.17.0