[PATCH v4 2/6] drm/i915/gt: Ensure memory quiesced before invalidation

[Matt Roper]

On Mon, Jul 17, 2023 at 07:30:55PM +0200, Andi Shyti wrote:
> From: Jonathan Cavitt <jonathan.cavitt at intel.com>
> 
> All memory traffic must be quiesced before requesting
> an aux invalidation on platforms that use Aux CCS.
> 
> Fixes: 972282c4cf24 ("drm/i915/gen12: Add aux table invalidate for all engines")
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
> Signed-off-by: Andi Shyti <andi.shyti at linux.intel.com>
> Cc: <stable at vger.kernel.org> # v5.8+
> ---
>  drivers/gpu/drm/i915/gt/gen8_engine_cs.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> index 563efee055602..bee3b7dc595cf 100644
> --- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> @@ -202,6 +202,13 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
>  {
>  	struct intel_engine_cs *engine = rq->engine;
>  
> +	/*
> +	 * Aux invalidations on Aux CCS platforms require
> +	 * memory traffic is quiesced prior.
> +	 */
> +	if ((mode & EMIT_INVALIDATE) && !HAS_FLAT_CCS(engine->i915))

It's a pre-existing mistake in drm-tip at the moment, but we shouldn't
assume !flatccs always implies auxccs.  PVC has neither, and there may
be other similar platforms in the future.  We should probably add a
helper function for AuxCCS, similar to what we added to the Xe driver
recently:

https://patchwork.freedesktop.org/patch/539304/?series=118334&rev=1


Matt


> +		mode |= EMIT_FLUSH;
> +
>  	if (mode & EMIT_FLUSH) {
>  		u32 flags = 0;
>  		int err;
> -- 
> 2.40.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation