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There exists a current workaround to prevent a hang on context switch should the ring go to sleep in the middle of the restore, WaProgramMiArbOnOffAroundMiSetContext (applicable to all gen7+). In spite of disabling arbitration (which prevents the ring from powering down during the critical section) we were still hitting hangs that had the hallmarks of the known erratum. That is we are still seeing hangs "on the last instruction in the context restore". By comparing -nightly (broken) with requests (working), we were able to deduce that it was the semaphore LRI cross-talk that reproduced the original failure. The key was that requests implemented deferred semaphore signalling, and disabling that, i.e. emitting the semaphore signal to every other ring after every batch restored the frequent hang. Explicitly disabling PSMI sleep on the RCS ring was insufficient, all the rings had to be awake to prevent the hangs. Fortunately, we can reduce the wakelock to the MI_SET_CONTEXT operation itself, and so should be able to limit the extra power implications. Since the MI_ARB_ON_OFF workaround is listed for all gen7 and above products, we should apply this extra hammer for all of the same platforms despite so far that we have only been able to reproduce the hang on certain ivb and hsw models. The last question is whether we want to always use the extra hammer or only when we know semaphores are in operation. At the moment, we only use LRI on non-RCS rings for semaphores, but that may change in the future with the possibility of reintroducing this bug under subtle conditions. v2: Make it explicit that the PSMI LRI are an extension to the original workaround for the other rings. v3: Bikeshedding variable names and whitespacing Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=80660 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83677 Cc: Simon Farnsworth <simon@farnz.org.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Tested-by: Peter Frühberger <fritsch@xbmc.org> Reviewed-by: Daniel Vetter <daniel@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula <jani.nikula@intel.com> |
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| amd | ||
| armada | ||
| ast | ||
| bochs | ||
| bridge | ||
| cirrus | ||
| exynos | ||
| gma500 | ||
| i2c | ||
| i810 | ||
| i915 | ||
| imx | ||
| mga | ||
| mgag200 | ||
| msm | ||
| nouveau | ||
| omapdrm | ||
| panel | ||
| qxl | ||
| r128 | ||
| radeon | ||
| rcar-du | ||
| savage | ||
| shmobile | ||
| sis | ||
| sti | ||
| tdfx | ||
| tegra | ||
| tilcdc | ||
| ttm | ||
| udl | ||
| via | ||
| vmwgfx | ||
| ati_pcigart.c | ||
| drm_agpsupport.c | ||
| drm_atomic_helper.c | ||
| drm_atomic.c | ||
| drm_auth.c | ||
| drm_bufs.c | ||
| drm_cache.c | ||
| drm_context.c | ||
| drm_crtc_helper.c | ||
| drm_crtc_internal.h | ||
| drm_crtc.c | ||
| drm_debugfs.c | ||
| drm_dma.c | ||
| drm_dp_helper.c | ||
| drm_dp_mst_topology.c | ||
| drm_drv.c | ||
| drm_edid_load.c | ||
| drm_edid.c | ||
| drm_encoder_slave.c | ||
| drm_fb_cma_helper.c | ||
| drm_fb_helper.c | ||
| drm_flip_work.c | ||
| drm_fops.c | ||
| drm_gem_cma_helper.c | ||
| drm_gem.c | ||
| drm_global.c | ||
| drm_hashtab.c | ||
| drm_info.c | ||
| drm_internal.h | ||
| drm_ioc32.c | ||
| drm_ioctl.c | ||
| drm_irq.c | ||
| drm_legacy.h | ||
| drm_lock.c | ||
| drm_memory.c | ||
| drm_mipi_dsi.c | ||
| drm_mm.c | ||
| drm_modes.c | ||
| drm_modeset_lock.c | ||
| drm_of.c | ||
| drm_panel.c | ||
| drm_pci.c | ||
| drm_plane_helper.c | ||
| drm_platform.c | ||
| drm_prime.c | ||
| drm_probe_helper.c | ||
| drm_rect.c | ||
| drm_scatter.c | ||
| drm_sysfs.c | ||
| drm_trace_points.c | ||
| drm_trace.h | ||
| drm_vm.c | ||
| drm_vma_manager.c | ||
| Kconfig | ||
| Makefile | ||