[Mesa-dev] [PATCH 1/5] i965/icl: Fix L3 configurations

[Francisco Jerez]

Anuj Phogat <anuj.phogat at gmail.com> writes:

> Use L3 configuration table specified in h/w specification.
>
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> Cc: Kenneth Graunke <kenneth at whitecape.org>
> Cc: Francisco Jerez <currojerez at riseup.net>
> Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>  src/intel/common/gen_l3_config.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/src/intel/common/gen_l3_config.c b/src/intel/common/gen_l3_config.c
> index b977c6ab136..079608198bc 100644
> --- a/src/intel/common/gen_l3_config.c
> +++ b/src/intel/common/gen_l3_config.c
> @@ -137,12 +137,16 @@ static const struct gen_l3_config cnl_l3_configs[] = {
>   */
>  static const struct gen_l3_config icl_l3_configs[] = {
>     /* SLM URB ALL DC  RO  IS   C   T */
> -   {{  0, 64, 64,  0,  0,  0,  0,  0 }},
> -   {{  0, 64,  0, 16, 48,  0,  0,  0 }},
> -   {{  0, 48,  0, 16, 64,  0,  0,  0 }},
> -   {{  0, 32,  0,  0, 96,  0,  0,  0 }},
> -   {{  0, 32, 96,  0,  0,  0,  0,  0 }},
> -   {{  0, 32,  0, 16, 80,  0,  0,  0 }},
> +   {{  0, 32, 32,  0,  0,  0,  0,  0 }},

This configuration is inherently inefficient since it will always leave
a third of the L3 cache unallocated.  According to the hardware docs
it's only included for backwards compatibility.  I think we should
remove it so we don't end up using it accidentally.

> +   {{  0, 32, 28,  0,  0,  0,  0,  0 }},
> +   {{  0, 24,  0,  8, 28,  0,  0,  0 }},
> +   {{  0, 16,  0,  0, 44,  0,  0,  0 }},
> +   {{  0, 16, 12,  0,  0,  0,  0,  0 }},
> +   {{  0, 16,  0,  0, 12,  0,  0,  0 }},

The configurations above won't work right now because we aren't setting
up the command buffer and tile cache-related partitions in the L3
control registers.  You either need to hook up the new partitions (and
add array entries for them in gen_l3_config), or remove/comment out the
five lines above.

> +   {{  0, 16, 80,  0,  0,  0,  0,  0 }},

From the results of the experiments we ran it seems like the last
configuration above is busted due to some hardware bug.  It would make
sense to remove or at least comment out the line so we don't use it
accidentally until we get some better workaround from the hardware team.

> +   {{  0, 16, 48,  0,  0,  0,  0,  0 }},
> +   {{  0, 16, 44,  0,  0,  0,  0,  0 }},

As before the above two configurations won't work due to the missing
partitions introduced in ICL.  With these changes in place there's
probably no need for PATCH 4 of this series.

> +   {{  0, 32, 64,  0,  0,  0,  0,  0 }},
>     {{  0 }}
>  };
>  
> -- 
> 2.17.1
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 227 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20181115/b1eb65ac/attachment.sig>