[Intel-gfx] [PATCH] drm/i915/guc: Prevent ggtt->invalidate assert during GuC reload

[Michel Thierry]

On 6/30/2017 10:41 AM, Michel Thierry wrote:
> The driver reloads the GuC firmware after full gpu reset or
> suspend/resume, but it never disables the GuC beforehand.
> This leads us to hit the assert inside i915_ggtt_enable_guc added
> by commit 04f7b24eccdf ("drm/i915/guc: Assert that we switch between
> known ggtt->invalidate functions").
> 

Ping...
I know this isn't important, since who is using guc? (I only know people 
who hates it).

Or we just remove the assert in i915_ggtt_enable_guc.

> As a workaround, don't call i915_ggtt_enable_guc if there is a GuC
> execbuf_client; because if there isn't one we are either loading in a
> fresh system or we called intel_uc_fini_hw.
> 
> I'm inclined to this approach because even if intel_uc_fini_hw could be
> added to the suspend path, we will still need to keep this for the
> full gpu reset case.
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Michal Winiarski <michal.winiarski at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Signed-off-by: Michel Thierry <michel.thierry at intel.com>
> ---
>   drivers/gpu/drm/i915/intel_uc.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uc.c b/drivers/gpu/drm/i915/intel_uc.c
> index a8930f2feacf..564b0d2b8842 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -339,8 +339,14 @@ int intel_uc_init_hw(struct drm_i915_private *dev_priv)
>          guc_disable_communication(guc);
>          gen9_reset_guc_interrupts(dev_priv);
> 
> -       /* We need to notify the guc whenever we change the GGTT */
> -       i915_ggtt_enable_guc(dev_priv);
> +       /*
> +        * We need to notify the guc whenever we change the GGTT; but if we
> +        * are reloading the firmware (after full gpu reset or suspend/resume),
> +        * we should skip this since gtt->invalidate was already set (or we hit
> +        * an assert).
> +        */
> +       if (!dev_priv->guc.execbuf_client)
> +               i915_ggtt_enable_guc(dev_priv);
> 
>          if (i915.enable_guc_submission) {
>                  /*
> --
> 2.11.0
> 
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