On 07.04.2014 17:16, Inki Dae wrote:
Hi Andrzej,
2014-04-07 23:18 GMT+09:00 Andrzej Hajda <a.hajda@xxxxxxxxxxx>:
Hi Inki and Tomasz,
On 04/06/2014 05:15 AM, Inki Dae wrote:
(...)
The code creating the list of components to wait for
(exynos_drm_add_components()) doesn't seem to consider which sub-drivers are
actually enabled in kernel config.
Are you sure?
exynos_drm_add_components() will try to attach components *added to
component_lists. And these components will be added by only
corresponding sub drivers to the component_lists and
master->components.
So in this case, if users disabled HDMI support then a commponent
object for HDMI sub driver doesn't exists in the component_lists and
master->components. This means that a component object for HDMI sub
driver *cannot be attached to master object*.
As a result, component_bind_add() will ignor component_bind call for
HDMI sub driver so HDMI driver will not be bounded. The only
components added by sub drivers will be bound, component->ops->bind().
For more understanding, it seems like you need to look into below codes,
static int exynos_drm_add_components(...)
{
...
for (i == 0;; i++) {
...
node = of_parse_phandle(np, "ports", i);
...
ret = component_master_add_child(m, compare_of, node);
...
}
}
Hmm, In case HDMI driver is not present, HDMI device is not probed and
HDMI component is not added, so component_master_add_child returns
an error when it tries to add hdmi component and master is never brought
up, am I correct?
Ok, after that,
ret = component_master_add(,..)
if (ret < 0)
DRM_DEBUG_KMS("re-tried by last sub driver probed later.\n");
As you can see above, if component_master_add() is failed, return 0,
*not error*. And then component_add() called by other kms drivers,
late probing of hdmi or fimd probing - if there is any kms driver
enabled - will try to bring up master again by calling
try_to_bring_up_master() from beginning.
And if component_list is empty then it means that there is no any kms
driver enabled.
Do you still think in that case, exynos drm initialization will be failed?
There will be no HDMI driver to call component_add(), because HDMI sub
driver will be disabled in kernel config and any previous
component_master_add_child() for the phandle pointing to HDMI node will
wail, because such component will never be registered.
The complete failure path is as follows:
exynos_drm_platform_probe()
component_master_add()
try_to_bring_up_master()
exynos_drm_add_components()
// phandle to HDMI node
component_master_add_child()
= -ENXIO
= -ENXIO
= 0 // but no call to master->ops->bind(master->dev);
= 0
= 0 // but Exynos DRM platform is not registered yet
Now if any other late-probed sub-driver comes, the sequence will be as
follows (let's take FIMD as an example):
fimd_probe()
component_add()
try_to_bring_up_masters()
try_to_bring_up_master()
exynos_drm_add_components()
// phandle to HDMI node
component_master_add_child()
= -ENXIO
= -ENXIO
= 0 // but no call to
// master->ops->bind(master->dev);
= 0
= 0
= 0 // but Exynos DRM platform still not registered
And the same for any late-probed driver, unless HDMI drivers loads, but
there is no HDMI driver, because it is disabled in kernel config and not
compiled in.
Best regards,
Tomasz
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