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The flip stall detector kicks in when pending>=INTEL_FLIP_COMPLETE. That means if we first call intel_prepare_page_flip() but don't call intel_finish_page_flip(), the next stall check will erroneosly think the page flip was somehow stuck. With enough debug spew emitted from the interrupt handler my 830 hangs when this happens. My theory is that the previous vblank interrupt gets sufficiently delayed that the handler will see the pending bit set in IIR, but ISR still has the bit set as well (ie. the flip was processed by CS but didn't complete yet). In this case the handler will proceed to call intel_check_page_flip() immediately after intel_prepare_page_flip(). It then tries to print a backtrace for the stuck flip WARN, which apparetly results in way too much debug spew delaying interrupt processing further. That then seems to cause an endless loop in the interrupt handler, and the machine is dead until the watchdog kicks in and reboots. At least limiting the number of iterations of the loop in the interrupt handler also prevented the hang. So it seems better to not call intel_prepare_page_flip() without immediately calling intel_finish_page_flip(). The IIR/ISR trickery avoids races here so this is a perfectly safe thing to do. v2: Fix typo in commit message (checkpatch) Cc: stable@vger.kernel.org Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88381 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85888 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com> |
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| 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 | ||