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/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c
index f7cf47b..d5d53aa 100644
--- a/drivers/gpu/drm/tegra/fb.c
+++ b/drivers/gpu/drm/tegra/fb.c
@@ -276,7 +276,6 @@
unsigned int num_crtc,
unsigned int max_connectors)
{
- struct drm_fb_helper *helper;
struct tegra_fbdev *fbdev;
int err;
@@ -286,8 +285,7 @@
return ERR_PTR(-ENOMEM);
}
- fbdev->base.funcs = &tegra_fb_helper_funcs;
- helper = &fbdev->base;
+ drm_fb_helper_prepare(drm, &fbdev->base, &tegra_fb_helper_funcs);
err = drm_fb_helper_init(drm, &fbdev->base, num_crtc, max_connectors);
if (err < 0) {