In order for gen8+ hardware to guarantee that no context switch takes place during engine reset and that current context is properly saved, the driver needs to notify and query hw before commencing with reset. There are gpu hangs where the engine gets so stuck that it never will report to be ready for reset. We could proceed with reset anyway, but with some hangs with skl, the forced gpu reset will result in a system hang. By inspecting the unreadiness for reset seems to correlate with the probable system hang. We will only proceed with reset if all engines report that they are ready for reset. If root cause for system hang is found and can be worked around with another means, we can reconsider if we can reinstate full reset for unreadiness case. v2: -EIO, Recovery, gen8 (Chris, Tomas, Daniel) v3: updated commit msg References: https://bugs.freedesktop.org/show_bug.cgi?id=89959 References: https://bugs.freedesktop.org/show_bug.cgi?id=90854 Testcase: igt/gem_concurrent_blit --r prw-blt-overwrite-source-read-rcs-forked Testcase: igt/gem_concurrent_blit --r gtt-blt-overwrite-source-read-rcs-forked Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: Tomas Elf <tomas.elf@xxxxxxxxx> Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_reg.h | 3 +++ drivers/gpu/drm/i915/intel_uncore.c | 45 ++++++++++++++++++++++++++++++++++++- 2 files changed, 47 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 0b979ad..3684f92 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -1461,6 +1461,9 @@ enum skl_disp_power_wells { #define RING_MAX_IDLE(base) ((base)+0x54) #define RING_HWS_PGA(base) ((base)+0x80) #define RING_HWS_PGA_GEN6(base) ((base)+0x2080) +#define RING_RESET_CTL(base) ((base)+0xd0) +#define RESET_CTL_REQUEST_RESET (1 << 0) +#define RESET_CTL_READY_TO_RESET (1 << 1) #define HSW_GTT_CACHE_EN 0x4024 #define GTT_CACHE_EN_ALL 0xF0007FFF diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 4a86cf0..6a19b3e 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -1455,9 +1455,52 @@ static int gen6_do_reset(struct drm_device *dev) return ret; } +static int wait_for_register(struct drm_i915_private *dev_priv, + const u32 reg, + const u32 mask, + const u32 value, + const unsigned long timeout) +{ + return wait_for((I915_READ(reg) & mask) == value, timeout); +} + +static int gen8_do_reset(struct drm_device *dev) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + struct intel_engine_cs *engine; + int ret, i; + + for_each_ring(engine, dev_priv, i) { + I915_WRITE(RING_RESET_CTL(engine->mmio_base), + _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET)); + + ret = wait_for_register(dev_priv, + RING_RESET_CTL(engine->mmio_base), + RESET_CTL_READY_TO_RESET, + RESET_CTL_READY_TO_RESET, + 700); + if (ret) { + DRM_ERROR("%s: reset request timeout\n", engine->name); + ret = -EIO; + goto not_ready; + } + } + + return gen6_do_reset(dev); + +not_ready: + for_each_ring(engine, dev_priv, i) + I915_WRITE(RING_RESET_CTL(engine->mmio_base), + _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET)); + + return ret; +} + static int (*intel_get_gpu_reset(struct drm_device *dev))(struct drm_device *) { - if (INTEL_INFO(dev)->gen >= 6) + if (INTEL_INFO(dev)->gen >= 8) + return gen8_do_reset; + else if (INTEL_INFO(dev)->gen >= 6) return gen6_do_reset; else if (IS_GEN5(dev)) return ironlake_do_reset; -- 1.9.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
