omapdrm (un)registers irqs inside an irq handler. The problem is that
the (un)register function uses dispc_runtime_get/put() to enable the
clocks, and those functions are not irq safe by default.
This was kind of fixed in 48664b21ae
(OMAPDSS: DISPC: set irq_safe for runtime PM), which makes dispc's
runtime calls irq-safe.
However, using pm_runtime_irq_safe in dispc makes the parent of dispc,
dss, always enabled, effectively preventing PM for the whole DSS module.
This patch makes omapdrm behave better by adding new irq (un)register
functions that do not use dispc_runtime_get/put, and using those
functions in interrupt context. Thus we can make dispc again
non-irq-safe, allowing proper PM.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Rob Clark <robdclark@gmail.com>
************************************************************
* 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
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