Hi
On Thu, Jan 23, 2014 at 9:52 AM, Daniel Vetter daniel.vetter@ffwll.ch wrote:
Driver modules really don't have much business frobbing around with this: Splitting up modeset resources (if we ever get around to enable this for real) should be something purely controlled and managed by the drm core in a driver-agnostic fashion. As usual imx disagrees, but that's due to the convoluted setup sequence. Russell King is working on a proper fix for that, so this patch needs to wait for those to land to avoid breaking imx.
I tried working on "modeset-object splitting" as part of the DRM-Master rework, but that's all really racy and we'd break current user-space. For instance the object-indices (compared to object-IDs) need to be constant, but with our current object-lists, removing an object will change indices (thus breaking possible_crtcs/encoders).
There are ways to make that work, but it'd require huge drm_crtc.c changes. And I also think our locking doesn't provide for that. Furthermore, resource-retrieval is not atomic (we need multiple ioctls: GetResources, GetCrtc, ...) so if we change the objects in between, we may break running apps in a subtle way.
So I'm all for making object-lists immutable after drm_dev_register() was called. Imo, hardware should wait for all sub-devices to be present and then call drm_dev_register(). Once the first sub-device is removed, you call drm_dev_unregister(). And I think that's what Russel's compound-device infrastructure does by hiding the sub-devices in a compound device.
If there's ever hardware that truly supports sub-device hotplugging, we can support that by adding a DRM-ClientCap like 3D modes. But as I understand, the current hardware is still a single piece of hardware which just might get probed via different buses and thus is not an atomic entity. So the device is still hotplugged as a whole, we just don't get the events through a single path.
Thanks David
Cc: Sascha Hauer s.hauer@pengutronix.de Cc: Russell King rmk+kernel@arm.linux.org.uk Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/drm_crtc.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index cf134540b675..98084413a842 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1264,7 +1264,6 @@ int drm_mode_group_init_legacy_group(struct drm_device *dev,
return 0;} -EXPORT_SYMBOL(drm_mode_group_init_legacy_group);
/**
- drm_crtc_convert_to_umode - convert a drm_display_mode into a modeinfo
-- 1.8.5.2
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