Hi Chris,
On Tue, Oct 01, 2019 at 02:54:02PM +0100, Chris Wilson wrote:
> Allow the user to restrict the available set of engines via a module
> parameter.
what is the driving reason for wanting this? Could you explain it
in the commit log?
It feels a bit confusing, though. You are actually making a
difference between engines we don't have and engines we don't
want, and I don't see why.
Wouldn't it make sense to either
- define a new architecture (which could make things more
confusing).
or
- have it specified in kernel configuration
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Stuart Summers <stuart.summers@xxxxxxxxx>
> Cc: Andi Shyti <andi.shyti@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Martin Peres <martin.peres@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/intel_engine_cs.c | 35 ++++++++++++++++-------
> drivers/gpu/drm/i915/i915_gem.c | 5 ++++
> drivers/gpu/drm/i915/i915_params.c | 4 +++
> drivers/gpu/drm/i915/i915_params.h | 1 +
> 4 files changed, 35 insertions(+), 10 deletions(-)
Because this is a module option that is set by the user, I don't
see any documentation about it.
> +static bool engine_available(struct drm_i915_private *i915, int id)
> +{
> + /* uAPI -- modparam bits must be consistent between kernels */
> + static const unsigned int param_bit[] = {
> + [RCS0] = BIT(0),
> + [VCS0] = BIT(1),
> + [BCS0] = BIT(2),
> + [VECS0] = BIT(3),
> + [VCS1] = BIT(4),
> + [VCS2] = BIT(5),
> + [VCS3] = BIT(6),
> + [VECS1] = BIT(7),
> + };
Yet another way to refer to engines... this time inside a static
function, without any visibility outside.
Andi
> +
> + if (!HAS_ENGINE(i915, id))
> + return false;
(engines we don't have...
> + if (!(i915_modparams.engines & param_bit[id]))
> + return false;
... engines we don't want)
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