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drm: don't call ->firstopen for KMS drivers 

It has way too much potential for driver writers to do stupid things
like delayed hw setup because the load sequence is somehow racy (e.g.
the imx driver in staging). So don't call it for modesetting drivers,
which reduces the complexity of the drm core -> driver interface a
notch.

v2: Don't forget to update DocBook.

v3: Go with Laurent's slightly more elaborate proposal for the DocBook
update. Add a few words on top of his diff to elaborate a bit on what
KMS drivers should and shouldn't do in lastclose. There was already a
paragraph present talking about restoring properties, I've simply
extended that one.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Daniel Vetter 2013-08-08 15:41:15 +02:00 committed by Dave Airlie
parent 0faa4a8777
commit 7d14bb6b53
2 changed files with 18 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
Documentation/DocBook/drm.tmpl
View File

@ -2405,18 +2405,18 @@ void (*postclose) (struct drm_device *, struct drm_file *);</synopsis>
</abstract>
<para>
The <methodname>firstopen</methodname> method is called by the DRM core
when an application opens a device that has no other opened file handle.
Similarly the <methodname>lastclose</methodname> method is called when
the last application holding a file handle opened on the device closes
it. Both methods are mostly used for UMS (User Mode Setting) drivers to
acquire and release device resources which should be done in the
<methodname>load</methodname> and <methodname>unload</methodname>
methods for KMS drivers.
for legacy UMS (User Mode Setting) drivers only when an application
opens a device that has no other opened file handle. UMS drivers can
implement it to acquire device resources. KMS drivers can't use the
method and must acquire resources in the <methodname>load</methodname>
method instead.
</para>
<para>
Note that the <methodname>lastclose</methodname> method is also called
at module unload time or, for hot-pluggable devices, when the device is
unplugged. The <methodname>firstopen</methodname> and
Similarly the <methodname>lastclose</methodname> method is called when
the last application holding a file handle opened on the device closes
it, for both UMS and KMS drivers. Additionally, the method is also
called at module unload time or, for hot-pluggable devices, when the
device is unplugged. The <methodname>firstopen</methodname> and
<methodname>lastclose</methodname> calls can thus be unbalanced.
</para>
<para>
@ -2445,7 +2445,12 @@ void (*postclose) (struct drm_device *, struct drm_file *);</synopsis>
<para>
The <methodname>lastclose</methodname> method should restore CRTC and
plane properties to default value, so that a subsequent open of the
device will not inherit state from the previous user.
device will not inherit state from the previous user. It can also be
used to execute delayed power switching state changes, e.g. in
conjunction with the vga-switcheroo infrastructure. Beyond that KMS
drivers should not do any further cleanup. Only legacy UMS drivers might
need to clean up device state so that the vga console or an independent
fbdev driver could take over.
</para>
</sect2>
<sect2>

3
drivers/gpu/drm/drm_fops.c
View File

@ -51,7 +51,8 @@ static int drm_setup(struct drm_device * dev)
int i;
int ret;
if (dev->driver->firstopen) {
if (dev->driver->firstopen &&
!drm_core_check_feature(dev, DRIVER_MODESET)) {
ret = dev->driver->firstopen(dev);
if (ret != 0)
return ret;