At least on ADLP a DC6 entry/exit sequence may corrupt the FPGA_DBG register's RM_NOCLAIM flag, which is used to detect incorrect MMIO accesses on the display RM bus. Based on my tests this only happens with a non-zero package C10 residency.
A related problem is that the DMC firmware's DC6->DC5 register state restore handler will keep alternately setting/clearing the RM_NOCLAIM flag (since it's a clear-on-write flag, which means clearing if the flag was set when saving the register value). Besides random triggering of unclaimed register access WARNs, I haven't noticed other issues. To avoid such WARNs disable the RM unclaimed checks while DC6 is enabled, until a firmware root-cause/fix is found. Signed-off-by: Imre Deak <[email protected]> --- .../i915/display/intel_display_power_well.c | 13 ++++++++ drivers/gpu/drm/i915/intel_uncore.c | 32 ++++++++++++++++++- drivers/gpu/drm/i915/intel_uncore.h | 3 ++ 3 files changed, 47 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_display_power_well.c b/drivers/gpu/drm/i915/display/intel_display_power_well.c index 916009894d89c..012d56ebcc02e 100644 --- a/drivers/gpu/drm/i915/display/intel_display_power_well.c +++ b/drivers/gpu/drm/i915/display/intel_display_power_well.c @@ -845,6 +845,15 @@ void skl_enable_dc6(struct drm_i915_private *dev_priv) intel_de_rmw(dev_priv, GEN8_CHICKEN_DCPR_1, 0, SKL_SELECT_ALTERNATE_DC_EXIT); + /* + * A DC6 exit sequence will corrupt the FPGA_DBG/RM noclaim flag on + * ADLP, so disable the unclaimed MMIO checking using this flag while + * DC6 is enabled. + * TODO: remove this once a firmware root-cause/fix is found. + */ + if (IS_ALDERLAKE_P(dev_priv)) + intel_uncore_disable_unclaimed_rm_check(&dev_priv->uncore); + gen9_set_dc_state(dev_priv, DC_STATE_EN_UPTO_DC6); } @@ -965,6 +974,10 @@ void gen9_disable_dc_states(struct drm_i915_private *dev_priv) if (!HAS_DISPLAY(dev_priv)) return; + if (IS_ALDERLAKE_P(dev_priv) && + power_domains->target_dc_state == DC_STATE_EN_UPTO_DC6) + intel_uncore_enable_unclaimed_rm_check(&dev_priv->uncore); + intel_cdclk_get_cdclk(dev_priv, &cdclk_config); /* Can't read out voltage_level so can't use intel_cdclk_changed() */ drm_WARN_ON(&dev_priv->drm, diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 796ebfe6c5507..8a33ac348ad5e 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -49,6 +49,7 @@ intel_uncore_mmio_debug_init_early(struct drm_i915_private *i915) { spin_lock_init(&i915->mmio_debug.lock); i915->mmio_debug.unclaimed_mmio_check = 1; + i915->mmio_debug.unclaimed_rm_check = true; i915->uncore.debug = &i915->mmio_debug; } @@ -504,6 +505,35 @@ intel_uncore_forcewake_reset(struct intel_uncore *uncore) return fw; /* track the lost user forcewake domains */ } +/** + * intel_uncore_disable_unclaimed_rm_check - disable unclaimed RM MMIO checks + * @uncore: the intel_uncore structure + * + * Disabling checking for unclaimed MMIO accesses on the display RM bus. + */ +void intel_uncore_disable_unclaimed_rm_check(struct intel_uncore *uncore) +{ + spin_lock_irq(&uncore->debug->lock); + uncore->debug->unclaimed_rm_check = false; + spin_unlock_irq(&uncore->debug->lock); +} + +/** + * intel_uncore_enable_unclaimed_rm_check - enable unclaimed RM MMIO checks + * @uncore: the intel_uncore structure + * + * Enable checking for unclaimed MMIO accesses on the display RM bus. + */ +void intel_uncore_enable_unclaimed_rm_check(struct intel_uncore *uncore) +{ + spin_lock_irq(&uncore->debug->lock); + + uncore->debug->unclaimed_rm_check = true; + __raw_uncore_write32(uncore, FPGA_DBG, FPGA_DBG_RM_NOCLAIM); + + spin_unlock_irq(&uncore->debug->lock); +} + static bool fpga_check_for_unclaimed_mmio(struct intel_uncore *uncore) { @@ -531,7 +561,7 @@ fpga_check_for_unclaimed_mmio(struct intel_uncore *uncore) __raw_uncore_write32(uncore, FPGA_DBG, FPGA_DBG_RM_NOCLAIM); - return true; + return uncore->debug->unclaimed_rm_check; } static bool diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h index 9ea1f4864a3a4..0c2be600ac423 100644 --- a/drivers/gpu/drm/i915/intel_uncore.h +++ b/drivers/gpu/drm/i915/intel_uncore.h @@ -44,6 +44,7 @@ struct intel_uncore_mmio_debug { int unclaimed_mmio_check; int saved_mmio_check; u32 suspend_count; + bool unclaimed_rm_check:1; }; enum forcewake_domain_id { @@ -245,6 +246,8 @@ void intel_uncore_prune_engine_fw_domains(struct intel_uncore *uncore, struct intel_gt *gt); bool intel_uncore_unclaimed_mmio(struct intel_uncore *uncore); bool intel_uncore_arm_unclaimed_mmio_detection(struct intel_uncore *uncore); +void intel_uncore_enable_unclaimed_rm_check(struct intel_uncore *uncore); +void intel_uncore_disable_unclaimed_rm_check(struct intel_uncore *uncore); void intel_uncore_cleanup_mmio(struct intel_uncore *uncore); void intel_uncore_fini_mmio(struct drm_device *dev, void *data); void intel_uncore_suspend(struct intel_uncore *uncore); -- 2.37.2
