After all relevant pipes are disabled and after we've updated all the
state with the staged state, but before we call the per-crtc
->mode_set functions there's a very natural point to set up any
shared/global resources like
- shared plls (obviously only the setup, the enabling needs to be
separately handling with a separate refcount)
- global watermark state like the DSPARB on gmch platforms
- workaround bits that depend upon the exact global output
configuration
- enabling the right set of refclocks
- enabling/disabling manual power wells.
Now for a lot of these things we can't move them into this function
yet, most often because we only compute the required information in
the per-crtc ->mode_set callback. Which is too late. But due to a
bunch of reasons (check-only atomic modeset, fastboot&hw state checks,
...) we need to separate the computation of that state from the actual
hw frobbery anyway. So we can move things into this new callback step-
by-step.
Others can't be moved here (or implemented at all) because our code
lacks the smarts to properly update them. E.g. the DSPARB can only be
updated when all pipes are disabled, so if we decide to change it's
value, we need to disable _all_ pipes. The infrastructure for that is
already in place (with the various pipe masks that driver the modeset
logic). But again we need to move a few things out of ->mode_set
first before we can even implement the correct decision making.
In any case, we need to start somewhere, so let's start with the
callback: Some small follow-up patches will make immediate good use of
it.
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
************************************************************
* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
************************************************************
The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html
47fab7370b