drm: Introduce drm_fb_helper_prepare()
To implement hotplug detection in a race-free manner, drivers must call
drm_kms_helper_poll_init() before hotplug events can be triggered. Such
events can be triggered right after any of the encoders or connectors
are initialized. At the same time, if the drm_fb_helper_hotplug_event()
helper is used by a driver, then the poll helper requires some parts of
the FB helper to be initialized to prevent a crash.
At the same time, drm_fb_helper_init() requires information that is not
necessarily available at such an early stage (number of CRTCs and
connectors), so it cannot be used yet.
Add a new helper, drm_fb_helper_prepare(), that initializes the bare
minimum needed to allow drm_kms_helper_poll_init() to execute and any
subsequent hotplug events to be processed properly.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
index cb01e16..cc0ae04 100644
--- a/drivers/gpu/drm/drm_fb_cma_helper.c
+++ b/drivers/gpu/drm/drm_fb_cma_helper.c
@@ -354,9 +354,10 @@
return ERR_PTR(-ENOMEM);
}
- fbdev_cma->fb_helper.funcs = &drm_fb_cma_helper_funcs;
helper = &fbdev_cma->fb_helper;
+ drm_fb_helper_prepare(dev, helper, &drm_fb_cma_helper_funcs);
+
ret = drm_fb_helper_init(dev, helper, num_crtc, max_conn_count);
if (ret < 0) {
dev_err(dev->dev, "Failed to initialize drm fb helper.\n");