On Tue, Aug 23, 2016 at 7:52 PM, Noralf Trønnes noralf@tronnes.org wrote:
+static int sdrm_fbdev_event_notify(struct notifier_block *self,
unsigned long action, void *data)+{
struct sdrm_device *sdrm;struct fb_event *event = data;struct fb_info *info = event->info;struct drm_fb_helper *fb_helper = info->par;if (action != FB_EVENT_FB_UNREGISTERED)return NOTIFY_DONE;if (!fb_helper || !fb_helper->dev || fb_helper->fbdev != info)return NOTIFY_DONE;sdrm = fb_helper->dev->dev_private;if (sdrm && sdrm->fb_helper == fb_helper)platform_device_del(to_platform_device(fb_helper->dev->dev));
return NOTIFY_DONE;+}
One problem this leaves behind is that registering of the new fbdev driver is too late - by that point we've already set up the entire driver, including modeset. If fbdev meanwhile does a dpms off or something like that all hell will break loose.
I don't understand how fbdev registration comes into play here. Drivers call remove_conflicting_framebuffers very early so simpledrm is gone by the time they register anything.
For simpledrm, fbdev doing blank/unblank is a no-op since fb_ops.fb_blank is not implemented. So a fb_blank() just results in fbcon doing a software blank.
Maybe my scenario wasn't entirely clear: - prereq: fbdev emulation in drm is disabled 1. simpledrm loads and sets up the firmware fb 2. real driver loads, first calls drm_fb_helper_remove_conflicting_framebuffer. Nothing happens because CONFIG_FB=n. 3. real driver start loading, remapping the gart and what not else 4. something is drawn using fbcon, simplerdrm writes through the now invalid mapping -> BOOM
You have code to listen to the framebuffer registration notifier, but I think even that happens way too late. Or at least I didn't spot any code in remove_conflicting_framebuffers which would call down into that notifier. Or maybe I entirely misunderstand your code ...
Wrt fixing: Just adding it to the recently added stub is of course also a working solution. -Daniel
PS: Can you pls review the 2 patches I submitted with you on cc? I won't merge my own patches without proper review, so without that done they're stuck.