On Wed, Mar 13, 2024 at 09:19:50PM +0100, Andi Shyti wrote:
> We want a fixed load CCS balancing consisting in all slices
> sharing one single user engine. For this reason do not create the
> intel_engine_cs structure with its dedicated command streamer for
> CCS slices beyond the first.
>
> Fixes: d2eae8e98d59 ("drm/i915/dg2: Drop force_probe requirement")
> Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
> Cc: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v6.2+
> ---
> drivers/gpu/drm/i915/gt/intel_engine_cs.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index f553cf4e6449..c4fb31bb6e72 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -966,6 +966,7 @@ int intel_engines_init_mmio(struct intel_gt *gt)
> const unsigned int engine_mask = init_engine_mask(gt);
> unsigned int mask = 0;
> unsigned int i, class;
> + u8 ccs_instance = 0;
> u8 logical_ids[MAX_ENGINE_INSTANCE + 1];
> int err;
>
> @@ -986,6 +987,19 @@ int intel_engines_init_mmio(struct intel_gt *gt)
> !HAS_ENGINE(gt, i))
> continue;
>
> + /*
> + * Do not create the command streamer for CCS slices
> + * beyond the first. All the workload submitted to the
> + * first engine will be shared among all the slices.
> + *
> + * Once the user will be allowed to customize the CCS
> + * mode, then this check needs to be removed.
> + */
> + if (IS_DG2(i915) &&
> + class == COMPUTE_CLASS &&
> + ccs_instance++)
> + continue;
Wouldn't it be more intuitive to drop the non-lowest CCS engines in
init_engine_mask() since that's the function that's dedicated to
building the list of engines we'll use? Then we don't need to kill the
assertion farther down either.
Matt
> +
> err = intel_engine_setup(gt, i,
> logical_ids[instance]);
> if (err)
> @@ -996,11 +1010,9 @@ int intel_engines_init_mmio(struct intel_gt *gt)
> }
>
> /*
> - * Catch failures to update intel_engines table when the new engines
> - * are added to the driver by a warning and disabling the forgotten
> - * engines.
> + * Update the intel_engines table.
> */
> - if (drm_WARN_ON(&i915->drm, mask != engine_mask))
> + if (mask != engine_mask)
> gt->info.engine_mask = mask;
>
> gt->info.num_engines = hweight32(mask);
> --
> 2.43.0
>
--
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation
