[Intel-gfx] [PATCH 3/8] drm/i915: Verify GT workaround state at runtime

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-11-30 11:31:56)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Since we now have all the GT workarounds in a table, by adding a simple
> shared helper function we can now verify that their values are still
> applied after some interesting events in the lifetime of the driver.
> 
> At this stage these are the driver initialization and engine reset.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c          |  4 +++
>  drivers/gpu/drm/i915/i915_gem.c          |  3 ++
>  drivers/gpu/drm/i915/intel_workarounds.c | 46 ++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_workarounds.h |  2 ++
>  4 files changed, 55 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 2f3dc1cf83a6..14d019c9455b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -53,6 +53,7 @@
>  #include "i915_vgpu.h"
>  #include "intel_drv.h"
>  #include "intel_uc.h"
> +#include "intel_workarounds.h"
>  
>  static struct drm_driver driver;
>  
> @@ -2362,6 +2363,9 @@ int i915_reset_engine(struct intel_engine_cs *engine, const char *msg)
>                 goto out;
>         }
>  
> +       /* Catch GT workarounds affected by engine reset. */
> +       intel_gt_workarounds_verify(engine->i915, engine->name);

I'd rather, quite strongly, not have this inside i915_reset_engine()
itself. i915_reset_engine() is [designed to be] called from atomic
context. Adding I915_READ() here is questionable. My preference is to
have all this inside selftests/intel_workarounds where we can cross
check the gt/all-engines after device reset and other engine reset.
-Chris