Add device_link from panel device (supplier) to drm device (consumer)
when drm_panel_attach() is called. This patch should protect the
master drm driver if an attached panel driver unbinds while it is in
use. The device_link should make sure the drm device is unbound before
the panel driver becomes unavailable.
The device_link is removed when drm_panel_detach() is called. The
drm_panel_detach() should be called by the consumer DRM driver, not the
panel driver, otherwise both drivers are racing to delete the same link.
Signed-off-by: Jyri Sarha <jsarha@xxxxxx>
Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
---
drivers/gpu/drm/drm_panel.c | 10 ++++++++++
include/drm/drm_panel.h | 1 +
2 files changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 29d2c74..7474045 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -24,6 +24,7 @@
#include <linux/err.h>
#include <linux/module.h>
+#include <drm/drm_device.h>
#include <drm/drm_crtc.h>
#include <drm/drm_panel.h>
@@ -101,6 +102,13 @@ int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector)
if (panel->connector)
return -EBUSY;
+ panel->link = device_link_add(connector->dev->dev, panel->dev, 0);
+ if (!panel->link) {
+ dev_err(panel->dev, "failed to link panel to %s\n",
+ dev_name(connector->dev->dev));
+ return -EINVAL;
+ }
+
panel->connector = connector;
panel->drm = connector->dev;
@@ -123,6 +131,8 @@ EXPORT_SYMBOL(drm_panel_attach);
*/
int drm_panel_detach(struct drm_panel *panel)
{
+ device_link_del(panel->link);
+
panel->connector = NULL;
panel->drm = NULL;
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 14ac240..26a1b5f 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -89,6 +89,7 @@ struct drm_panel {
struct drm_device *drm;
struct drm_connector *connector;
struct device *dev;
+ struct device_link *link;
const struct drm_panel_funcs *funcs;
--
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