Re: [PATCH v2] drm/i915: Add the predicate source registers to the register whitelist

[Neil Roberts <neil@linux.intel.com>]

Hi,

Daniel Vetter <daniel@ffwll.ch> writes:

> Ok, I've merged this one, since that means you at least won't get an
> -EINVAL. But you can't yet enable the feature in mesa since it's still
> no-opped out. Let's hope that v3 actually starts granting rights (but
> please don't encode that in any merge mesa patch before it's official in
> the kernel, Dave Airlie _will_ revert it even if it breaks the build) and
> that this happens soon.

Thanks for merging the patch.

The current patch proposed for Mesa only enables the feature if the
version is >= 2 *and* it can successfully do a pipeline write to some
other register. Checking whether it can write to a register is already
used to decide whether to enable some transform feedback extensions and
indirect draw calls. I think in that case it should be safe to land the
Mesa patches even though it would only work on IvyBridge and not Haswell
or Gen8+. If we fix the kernel to allow the write for Haswell too then I
think it would magically start working without any extra changes. I'm
not really sure if I understand what you're saying about it being
no-opped. It's effectively not no-opped on IvyBridge so I think we
should already be able to enable the feature. Do you agree?

- Neil

> -Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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