Mika Kuoppala <[email protected]> writes:

> ELK seems to very picky about the preconditions to reset.
> Evidence on Eaglelake (8086:2e12 (rev 03)) shows that it does
> not like if reset occurs when there is active ring.
>
> Ville found out that there is workaround with name
> 'WaMediaResetMainRingCleanup' which suggests that we need to
> cleanup rings before resetting. It is unclear what cleanup
> exactly means but evidence shows that stopping the ring
> does have an effect on reset reliability.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100998

This is wrong. Should be
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100942

> Suggested-by: Ville Syrjälä <[email protected]>
> Cc: Ville Syrjälä <[email protected]>
> Cc: Chris Wilson <[email protected]>
> Cc: Tomi Sarvela <[email protected]>
> Signed-off-by: Mika Kuoppala <[email protected]>
> ---
>  drivers/gpu/drm/i915/intel_uncore.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c 
> b/drivers/gpu/drm/i915/intel_uncore.c
> index 7eaaf2225e1a..1d473cd1f8a4 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -1427,6 +1427,26 @@ int i915_reg_read_ioctl(struct drm_device *dev,
>       return ret;
>  }
>  
> +static void gen3_stop_rings(struct drm_i915_private *dev_priv)
> +{
> +     struct intel_engine_cs *engine;
> +     enum intel_engine_id id;
> +
> +     for_each_engine(engine, dev_priv, id) {
> +             const i915_reg_t mode_r = RING_MI_MODE(engine->mmio_base);
> +
> +             I915_WRITE_FW(mode_r, _MASKED_BIT_ENABLE(STOP_RING));
> +             if (intel_wait_for_register_fw(dev_priv,
> +                                            mode_r,
> +                                            MODE_IDLE,
> +                                            MODE_IDLE,
> +                                            1000)) {
> +                     DRM_DEBUG("%s : timed out STOP_RING\n",
> +                               engine->name);
> +             }
> +     }
> +}
> +
>  static bool i915_reset_complete(struct pci_dev *pdev)
>  {
>       u8 gdrst;
> @@ -1472,6 +1492,12 @@ static int g4x_do_reset(struct drm_i915_private 
> *dev_priv, unsigned engine_mask)
>       I915_WRITE(VDECCLK_GATE_D, I915_READ(VDECCLK_GATE_D) | 
> VCP_UNIT_CLOCK_GATE_DISABLE);
>       POSTING_READ(VDECCLK_GATE_D);
>  
> +     /* We stop engines, otherwise we might get failed reset and a
> +      * dead gpu (on elk).
> +      */
> +     /* WaMediaResetMainRingCleanup:ctg,elk (supposedly) */
> +     gen3_stop_rings(dev_priv);
> +
>       pci_write_config_byte(pdev, I915_GDRST,
>                             GRDOM_MEDIA | GRDOM_RESET_ENABLE);
>       ret =  wait_for(g4x_reset_complete(pdev), 500);
> -- 
> 2.11.0
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