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The current radeon driver initialization routines, when using KMS, are written so that the IRQ installation routine is called before initializing the WB buffer and the CP rings. With some ASICs, though, the IRQ routine tries to access the GFX_INDEX ring causing a call to RREG32 with the value of -1 in radeon_fence_read. This, in turn causes the system to completely hang with some cards, requiring a hard reset. A call stack that can cause such a hang looks like this (using rv515 ASIC for the example here): * rv515_init (rv515.c) * radeon_irq_kms_init (radeon_irq_kms.c) * drm_irq_install (drm_irq.c) * radeon_driver_irq_preinstall_kms (radeon_irq_kms.c) * rs600_irq_process (rs600.c) * radeon_fence_process - due to SW interrupt (radeon_fence.c) * radeon_fence_read (radeon_fence.c) * hang due to RREG32(-1) The patch moves the IRQ installation to the card startup routine, after the ring has been initialized, but before the IRQ has been set. This fixes the issue, but requires a check to see if the IRQ is already installed, as is the case in the system resume codepath. I have tested the patch on three machines using the rv515, the rv770 and the evergreen ASIC. They worked without issues. This seems to be a known issue and has been reported on several bug tracking sites by various distributions (see links below). Most of reports recommend booting the system with KMS disabled and then enabling KMS by reloading the radeon module. For some reason, this was indeed a usable workaround, however, UMS is now deprecated and disabled by default. Bug reports: https://bugzilla.redhat.com/show_bug.cgi?id=845745 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/561789 https://bbs.archlinux.org/viewtopic.php?id=156964 Signed-off-by: Adis Hamzić <adis@hamzadis.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Cc: stable@vger.kernel.org
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* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
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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