linux/drivers/gpu/drm
Daniel Vetter d1b28a26ed drm/i915: fix overlay on i830M
commit a9193983f4 upstream.

The overlay on the i830M has a peculiar failure mode: It works the
first time around after boot-up, but consistenly hangs the second time
it's used.

Chris Wilson has dug out a nice errata:

"1.5.12 Clock Gating Disable for Display Register
Address Offset:	06200h–06203h

"Bit 3
Ovrunit Clock Gating Disable.
0 = Clock gating controlled by unit enabling logic
1 = Disable clock gating function
DevALM Errata ALM049: Overlay Clock Gating Must be Disabled:  Overlay
& L2 Cache clock gating must be disabled in order to prevent device
hangs when turning off overlay.SW must turn off Ovrunit clock gating
(6200h) and L2 Cache clock gating (C8h)."

Now I've nowhere found that 0xc8 register and hence couldn't apply the
l2 cache workaround. But I've remembered that part of the magic that
the OVERLAY_ON/OFF commands are supposed to do is to rearrange cache
allocations so that the overlay scaler has some scratch space.

And while pondering how that could explain the hang the 2nd time we
enable the overlay, I've remembered that the old ums overlay code did
_not_ issue the OVERLAY_OFF cmd.

And indeed, disabling the OFF cmd results in the overlay working
flawlessly, so I guess we can workaround the lack of the above
workaround by simply never disabling the overlay engine once it's
enabled.

Note that we have the first part of the above w/a already implemented
in i830_init_clock_gating - leave that as-is to avoid surprises.

v2: Add a comment in the code.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=47827
Tested-by: Rhys <rhyspuk@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[bwh: Backported to 3.2:
 - Adjust context
 - s/intel_ring_emit(ring, /OUT_RING(/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-26 11:38:01 -08:00
..
exynos Merge branch 'exynos-drm-fixes' of git://git.infradead.org/users/kmpark/linux-2.6-samsung into drm-fixes 2012-04-27 08:20:35 +01:00
gma500 gma500: don't register the ACPI video bus 2012-06-17 11:21:28 -07:00
i2c drm: add convenience function to create an range property 2012-02-09 10:15:25 +00:00
i810 kill mm argument of vm_munmap() 2012-04-21 01:58:20 -04:00
i915 drm/i915: fix overlay on i830M 2012-11-26 11:38:01 -08:00
mga drm: move pci bus master enable into driver. 2012-02-16 18:31:07 +00:00
nouveau drm/nouveau: headless mode by default if pci class != vga display 2012-11-05 09:50:42 +01:00
r128 drm: move pci bus master enable into driver. 2012-02-16 18:31:07 +00:00
radeon drm/radeon: fix logic error in atombios_encoders.c 2012-11-26 11:37:45 -08:00
savage drm/savage: re-add busmaster enable, regression fix 2012-10-13 05:38:46 +09:00
sis drm sis: initialize object_idr 2012-06-22 11:36:53 -07:00
tdfx drm: Make the per-driver file_operations struct const 2011-11-11 11:14:47 +00:00
ttm ttm: Clear the ttm page allocated from high memory zone correctly 2012-11-26 11:37:45 -08:00
udl drm/udl: fix stride issues scanning out stride != width*bpp 2012-11-17 13:16:03 -08:00
via drm via: initialize object_idr 2012-06-22 11:36:53 -07:00
vmwgfx drm/vmwgfx: Fix a case where the code would BUG when trying to pin GMR memory 2012-11-17 13:16:34 -08:00
ati_pcigart.c gpu: Add export.h as required to drivers/gpu files. 2011-10-31 19:32:03 -04:00
drm_agpsupport.c drm: kill drm_agp_chipset_flush 2010-11-23 20:14:44 +00:00
drm_auth.c drm: Fix authentication kernel crash 2012-01-25 09:27:45 +00:00
drm_buffer.c gpu: Add export.h as required to drivers/gpu files. 2011-10-31 19:32:03 -04:00
drm_bufs.c VM: add "vm_mmap()" helper function 2012-04-20 17:29:13 -07:00
drm_cache.c drm: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:17 +08:00
drm_context.c drm: make DRM_UNLOCKED ioctls with their own mutex 2012-01-05 14:43:02 +00:00
drm_crtc_helper.c drm: allow loading an EDID as firmware to override broken monitor 2012-03-20 10:09:28 +00:00
drm_crtc.c drm: Destroy the planes prior to destroying the associated CRTC 2012-10-13 05:38:52 +09:00
drm_debugfs.c drm: serialize access to list of debugfs files 2011-11-11 11:05:19 +00:00
drm_dma.c gpu: Add export.h as required to drivers/gpu files. 2011-10-31 19:32:03 -04:00
drm_dp_i2c_helper.c
drm_drv.c drm: base prime/dma-buf support (v5) 2012-03-30 11:52:44 +01:00
drm_edid_load.c drm: allow loading an EDID as firmware to override broken monitor 2012-03-20 10:09:28 +00:00
drm_edid_modes.h drm/edid: support CEA video modes. 2011-12-19 14:53:16 +00:00
drm_edid.c drm/edid: don't return stack garbage from supports_rb 2012-07-16 09:04:05 -07:00
drm_encoder_slave.c gpu: add module.h to drivers/gpu files as required. 2011-10-31 19:32:03 -04:00
drm_fb_helper.c drm: Validate requested virtual size against allocated fb size 2012-04-03 11:18:46 +01:00
drm_fops.c drm: restore open_count if drm_setup fails 2012-11-17 13:16:12 -08:00
drm_gem.c drm: base prime/dma-buf support (v5) 2012-03-30 11:52:44 +01:00
drm_global.c
drm_hashtab.c gpu: Add export.h as required to drivers/gpu files. 2011-10-31 19:32:03 -04:00
drm_info.c Merge remote branch 'intel/drm-intel-next' of ../drm-next into drm-core-next 2011-03-14 14:15:13 +10:00
drm_ioc32.c drivers/gpu/drm/drm_ioc32.c: initialize all fields 2012-02-03 09:47:32 +00:00
drm_ioctl.c drm: add some caps for userspace to discover more info for dumb KMS driver (v2) 2012-02-16 18:35:11 +00:00
drm_irq.c drm: remove unused code 2012-02-29 10:18:29 +00:00
drm_lock.c drm: add missing exports for i810 driver. 2011-12-22 19:09:01 +00:00
drm_memory.c drm: remove unused code 2012-02-29 10:18:29 +00:00
drm_mm.c gpu: Add export.h as required to drivers/gpu files. 2011-10-31 19:32:03 -04:00
drm_modes.c drm: Add drm_mode_copy() 2012-03-15 09:52:51 +00:00
drm_pci.c drm: move pci bus master enable into driver. 2012-02-16 18:31:07 +00:00
drm_platform.c drm: cope with platformdev->id == -1 2012-03-07 14:03:40 +00:00
drm_prime.c drm: base prime/dma-buf support (v5) 2012-03-30 11:52:44 +01:00
drm_proc.c gpu: Add export.h as required to drivers/gpu files. 2011-10-31 19:32:03 -04:00
drm_scatter.c drivers: use kzalloc/kcalloc instead of 'kmalloc+memset', where possible 2011-07-25 20:57:13 -07:00
drm_stub.c drm/usb: move usb support into a separate module 2012-03-20 06:59:29 +00:00
drm_sysfs.c drm/sysfs: protect sysfs removal code against being run twice. 2012-03-15 13:35:31 +00:00
drm_trace_points.c
drm_trace.h
drm_usb.c drm/usb: fix module license on drm/usb layer. 2012-04-19 09:33:32 +01:00
drm_vm.c drm: add core support for unplugging a device (v2) 2012-03-15 13:35:33 +00:00
Kconfig drm: base prime/dma-buf support (v5) 2012-03-30 11:52:44 +01:00
Makefile drm: base prime/dma-buf support (v5) 2012-03-30 11:52:44 +01:00
README.drm

************************************************************
* 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