drm/panel: Make of_drm_find_panel() return an ERR_PTR() instead of NULL
Right now, the DRM panel logic returns NULL when a panel pointing to
the passed OF node is not present in the list of registered panels.
Most drivers interpret this NULL value as -EPROBE_DEFER, but we are
about to modify the semantic of of_drm_find_panel() and let the
framework return -ENODEV when the device node we're pointing to has
a status property that is not equal to "okay" or "ok".
Let's first patch the of_drm_find_panel() implementation to return
ERR_PTR(-EPROBE_DEFER) instead of NULL and patch all callers to replace
the '!panel' check by an 'IS_ERR(panel)' one.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180509130042.9435-2-boris.brezillon@bootlin.com
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 965530a..7e5530a0 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -151,7 +151,9 @@ EXPORT_SYMBOL(drm_panel_detach);
* tree node. If a matching panel is found, return a pointer to it.
*
* Return: A pointer to the panel registered for the specified device tree
- * node or NULL if no panel matching the device tree node can be found.
+ * node or an ERR_PTR() if no panel matching the device tree node can be found.
+ * The only error that can be reported is -EPROBE_DEFER, meaning that the panel
+ * device has not been probed yet, and the caller should retry later.
*/
struct drm_panel *of_drm_find_panel(const struct device_node *np)
{
@@ -167,7 +169,7 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
}
mutex_unlock(&panel_lock);
- return NULL;
+ return ERR_PTR(-EPROBE_DEFER);
}
EXPORT_SYMBOL(of_drm_find_panel);
#endif
