From: Jyri Sarha Date: Thu, 26 Apr 2018 11:07:00 +0300 Subject: drm/panel: Add device_link from panel device to DRM device Git-commit: 0c08754b59da5557532d946599854e6df28edc22 Patch-mainline: v4.19-rc1 References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166 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 Reviewed-by: Eric Anholt Signed-off-by: Thierry Reding Link: https://patchwork.freedesktop.org/patch/msgid/b53584fd988d045c13de22d81825395b0ae0aad7.1524727888.git.jsarha@ti.com Acked-by: Petr Tesarik --- drivers/gpu/drm/drm_panel.c | 10 ++++++++++ include/drm/drm_panel.h | 1 + 2 files changed, 11 insertions(+) --- a/drivers/gpu/drm/drm_panel.c +++ b/drivers/gpu/drm/drm_panel.c @@ -24,6 +24,7 @@ #include #include +#include #include #include @@ -104,6 +105,13 @@ int drm_panel_attach(struct drm_panel *p 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; @@ -125,6 +133,8 @@ EXPORT_SYMBOL(drm_panel_attach); */ int drm_panel_detach(struct drm_panel *panel) { + device_link_del(panel->link); + panel->connector = NULL; panel->drm = NULL; --- 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;