[Mesa-dev] [PATCH 1/2] i965: Fix broxton 2x6 l3 config

[Anuj Phogat]

On Mon, Jun 12, 2017 at 11:10 AM, Francisco Jerez <currojerez at riseup.net> wrote:
> Anuj Phogat <anuj.phogat at gmail.com> writes:
>
>> The new table added in this patch matches with the table
>> in gfxspecs. We were programming the wrong values earlier.
>>
>> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
>> Cc: Francisco Jerez <currojerez at riseup.net>
>> Cc: "17.1" <mesa-stable at lists.freedesktop.org>
>> ---
>>  src/intel/common/gen_device_info.c |  1 +
>>  src/intel/common/gen_device_info.h |  1 +
>>  src/intel/common/gen_l3_config.c   | 19 +++++++++++++++++++
>>  3 files changed, 21 insertions(+)
>>
>> diff --git a/src/intel/common/gen_device_info.c b/src/intel/common/gen_device_info.c
>> index 75284a6..eccb464 100644
>> --- a/src/intel/common/gen_device_info.c
>> +++ b/src/intel/common/gen_device_info.c
>> @@ -502,6 +502,7 @@ static const struct gen_device_info gen_device_info_bxt = {
>>
>>  static const struct gen_device_info gen_device_info_bxt_2x6 = {
>>     GEN9_LP_FEATURES_2X6,
>> +   .is_broxton_2x6 = 1,
>>     .l3_banks = 1,
>>  };
>>  /*
>> diff --git a/src/intel/common/gen_device_info.h b/src/intel/common/gen_device_info.h
>> index 6207630..4fe1b21 100644
>> --- a/src/intel/common/gen_device_info.h
>> +++ b/src/intel/common/gen_device_info.h
>> @@ -41,6 +41,7 @@ struct gen_device_info
>>     bool is_haswell;
>>     bool is_cherryview;
>>     bool is_broxton;
>> +   bool is_broxton_2x6;
>
> I don't think this boolean flag is useful.  The hardware spec refers to
> the validated configurations that apply to BXT 2x6 as relevant to all
> products with a single bank, which means you should probably check for
> gen >= 9 and l3_banks == 1 instead.
>
Right. I'll drop is_broxton_2x6 variable in V2.
>>     bool is_kabylake;
>>
>>     bool has_hiz_and_separate_stencil;
>> diff --git a/src/intel/common/gen_l3_config.c b/src/intel/common/gen_l3_config.c
>> index ae31d08..e17994b 100644
>> --- a/src/intel/common/gen_l3_config.c
>> +++ b/src/intel/common/gen_l3_config.c
>> @@ -102,6 +102,23 @@ static const struct gen_l3_config chv_l3_configs[] = {
>>  };
>>
>>  /**
>> + * BXT 2x6 validated L3 configurations.  \sa ivb_l3_configs.
>> + * Number of ways =
>> + *    Allocation in KB for SKU / (Way size per bank * Number of banks).
>
> Is this formula relevant?  The way size per bank is not really
> documented in the BSpec so it doesn't really give the reader any
> additional useful information.
>
It is not documented with name "way size per bank" but we have enough
comments suggesting the "size increments per bank" for different intel
h/w.

For CNL L3CNTLREG says:
"Increments of 2KB Per bank (L3 size needs to be calculated based on bank
  count per SKU)."

For SKL "L3 Bank Configuration" section says:
"Each L3 bank is identical as described below."
For MultiBank SKUs:
"Up to 64 ways, up to 128KB, tagged for L3"
which computes to 2KB increments per bank.

How about using Size increment per bank ? or any other name you suggest?
Number of ways =
   Allocation in KB for SKU / (Size increment per bank * Number of banks)

I find above comment useful to explain the numbers in below table.
We have a single table applicable to multiple SKUs and searching the
documents every time you want to verify these tables is time
consuming. I would like to add the similar comment to other
gen_l3_config tables as well.

>> + * For BXT 2x6: Banks = 1, Way size per bank = 4.
>> + */
>> +static const struct gen_l3_config bxt_2x6_l3_configs[] = {
>> +   /*SLM URB  All DC  RO  IS   C   T */
>> +   {{  0, 32, 48,  0,  0,  0,  0,  0 }},
>> +   {{  0, 32,  0,  8, 40,  0,  0,  0 }},
>> +   {{  0, 32,  0, 32, 16,  0,  0,  0 }},
>> +   {{ 16, 16, 48,  0,  0,  0,  0,  0 }},
>> +   {{ 16, 16,  0, 40,  8,  0,  0,  0 }},
>> +   {{ 16, 16,  0, 16, 32,  0,  0,  0 }},
>> +   {{ 0 }}
>> +};
>> +
>> +/**
>>   * Return a zero-terminated array of validated L3 configurations for the
>>   * specified device.
>>   */
>> @@ -117,6 +134,8 @@ get_l3_configs(const struct gen_device_info *devinfo)
>>
>>     case 9:
>>     case 10:
>> +      if (devinfo->is_broxton_2x6)
>> +         return bxt_2x6_l3_configs;
>>        return chv_l3_configs;
>>
>>     default:
>> --
>> 2.9.3