Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> Following a GPU reset, we may leave the context in a poorly defined
> state, and reloading from that context will leave the GPU flummoxed. For
> secondary contexts, this will lead to that context being banned - but
> currently it is also causing the default context to become banned,
> leading to turmoil in the shared state.
>
> This is a regression from
>
> commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1]
> Author: Ben Widawsky <benjamin.widawsky@xxxxxxxxx>
> Date: Mon Mar 16 16:00:58 2015 +0000
>
> drm/i915: Initialize all contexts
>
> which quietly introduced the removal of the MI_RESTORE_INHIBIT on the
> default context.
>
> v2: Mark the global default context as uninitialized on GPU reset so
> that the context-local workarounds are reloaded upon re-enabling.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 43761c5bcaca..f024d5d2c746 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev)
> i915_gem_context_unreference(lctx);
> ring->last_context = NULL;
> }
> +
> + /* Force the GPU state to be reinitialised on enabling */
> + if (ring->default_context)
> + ring->default_context->legacy_hw_ctx.initialized = false;
> }
> }
>
> @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req)
> if (ret)
> goto unpin_out;
>
> - if (!to->legacy_hw_ctx.initialized) {
> + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) {
> hw_flags |= MI_RESTORE_INHIBIT;
> /* NB: If we inhibit the restore, the context is not allowed to
> * die because future work may end up depending on valid address
> --
> 2.6.2
>
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