Re: [PATCH] drm/i915/gt: Fix CCS id's calculation for CCS mode setting

[Andi Shyti <andi.shyti@linux.intel.com>]

Hi,

On Fri, May 17, 2024 at 11:06:16AM +0200, Andi Shyti wrote:
> The whole point of the previous fixes has been to change the CCS
> hardware configuration to generate only one stream available to
> the compute users. We did this by changing the info.engine_mask
> that is set during device probe, reset during the detection of
> the fused engines, and finally reset again when choosing the CCS
> mode.
> 
> We can't use the engine_mask variable anymore, as with the
> current configuration, it imposes only one CCS no matter what the
> hardware configuration is.
> 
> Before changing the engine_mask for the third time, save it and
> use it for calculating the CCS mode.
> 
> After the previous changes, the user reported a performance drop
> to around 1/4. We have tested that the compute operations, with
> the current patch, have improved by the same factor.
> 
> Fixes: 6db31251bb26 ("drm/i915/gt: Enable only one CCS for compute workload")
> Cc: Chris Wilson <chris.p.wilson@linux.intel.com>
> Cc: Gnattu OC <gnattuoc@me.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Tested-by: Jian Ye <jian.ye@intel.com>

of course:

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>

Andi