[PATCH 4.2.y-ckt 119/268] drm/i915: Restore inhibiting the load of the default context

From: Kamal Mostafa
Date: Wed Jan 27 2016 - 16:33:33 EST


4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

commit 06ef83a705a98da63797a5a570220b6ca36febd4 upstream.

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>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1448630935-27377-1-git-send-email-chris@xxxxxxxxxxxxxxxxxx
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
[danvet: This seems to fix a gpu hand on after the first resume,
resulting in any future suspend operation failing with -EIO because
the gpu seems to be in a funky state. Somehow this patch fixes that.]
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
(cherry picked from commit 42f1cae8c079bcceb3cff079fddc3ff8852c788f)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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 48afa77..2d96da6 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -317,6 +317,10 @@ 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;
}
}

@@ -685,7 +689,7 @@ static int do_switch(struct intel_engine_cs *ring,
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
--
1.9.1