Re: [RFC 01/21] Bug: missing i915_seqno_passed() call?

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Oct 06, 2014 at 03:15:05PM +0100, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
> 
> ---
>  drivers/gpu/drm/i915/i915_gem.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 2a5351d..8c68219 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2886,7 +2886,7 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
>  	seqno = obj->last_read_seqno;
>  	/* Optimization: Avoid semaphore sync when we are sure we already
>  	 * waited for an object with higher seqno */
> -	if (seqno <= from->semaphore.sync_seqno[idx])
> +	if (seqno <= from->semaphore.sync_seqno[idx]) /* <--- broken?! needs to use i915_seqno_passed()??? */

No, becuase hw semaphores don't wrap around so we actual need to check for
<=, not the wrap-around logic seqno_passed has. If you feel like pls
submit a patch to add a comment here.

btw you're threading looks a bit funny, instead of patches all being
in-reply-to the cover letter they're all in-reply-to the previous patch.
Presuming you don't have a funky .gitconfig recent git should do this in
the preferred form by default.
-Daniel

>  		return 0;
>  
>  	ret = i915_gem_check_olr(obj->ring, seqno);
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch