[PATCH] drm/i915: Mark wait_for_engine() as maybe_unused

[PATCH] drm/i915: Mark wait_for_engine() as maybe_unused

[Matthias Kaehlcke]

The only call of wait_for_engine() is wrapped in a GEM_WARN_ON macro,
which confusingly suppresses the call unless CONFIG_DRM_I915_DEBUG_GEM
is set.

According to http://www.spinics.net/lists/intel-gfx/msg128768.html the
current behavior is correct, even though it's not obvious. Different
solutions to improve GEM_WARN_ON were discussed, but no conclusion
was reached.

Mark wait_for_engine() as maybe_unused to avoid a compiler warning,
according to the above discussion this is still needed evein if
GEM_WARN_ON is eventually refactored.

Reported-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
 drivers/gpu/drm/i915/i915_gem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 969bac8404f1..52d0b7d0082b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3364,7 +3364,8 @@ static int wait_for_timeline(struct i915_gem_timeline *tl, unsigned int flags)
 	return 0;
 }
 
-static int wait_for_engine(struct intel_engine_cs *engine, int timeout_ms)
+static __maybe_unused int wait_for_engine(
+	struct intel_engine_cs *engine, int timeout_ms)
 {
 	return wait_for(intel_engine_is_idle(engine), timeout_ms);
 }
-- 
2.14.1.342.g6490525c54-goog

Re: [PATCH] drm/i915: Mark wait_for_engine() as maybe_unused

[Nick Desaulniers]

Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>

Re: [PATCH] drm/i915: Mark wait_for_engine() as maybe_unused

[Daniel Vetter]

On Fri, Aug 25, 2017 at 10:09:45AM -0700, Matthias Kaehlcke wrote:
> The only call of wait_for_engine() is wrapped in a GEM_WARN_ON macro,
> which confusingly suppresses the call unless CONFIG_DRM_I915_DEBUG_GEM
> is set.
> 
> According to http://www.spinics.net/lists/intel-gfx/msg128768.html the
> current behavior is correct, even though it's not obvious. Different
> solutions to improve GEM_WARN_ON were discussed, but no conclusion
> was reached.
> 
> Mark wait_for_engine() as maybe_unused to avoid a compiler warning,
> according to the above discussion this is still needed evein if
> GEM_WARN_ON is eventually refactored.
> 
> Reported-by: Nick Desaulniers <nick.desaulniers@gmail.com>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

Seems to be taken care of already in

commit cad9946c2a4375386062131858881cfd30fc1b8f
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Sat Aug 26 12:09:33 2017 +0100

    drm/i915: Always sanity check engine state upon idling

Cheers, Daniel
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 969bac8404f1..52d0b7d0082b 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3364,7 +3364,8 @@ static int wait_for_timeline(struct i915_gem_timeline *tl, unsigned int flags)
>  	return 0;
>  }
>  
> -static int wait_for_engine(struct intel_engine_cs *engine, int timeout_ms)
> +static __maybe_unused int wait_for_engine(
> +	struct intel_engine_cs *engine, int timeout_ms)
>  {
>  	return wait_for(intel_engine_is_idle(engine), timeout_ms);
>  }
> -- 
> 2.14.1.342.g6490525c54-goog
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch