[Intel-gfx] [PATCH] drm/i915/slpc: Use platform limits for min/max frequency

[Belgaumkar, Vinay]

On 10/13/2022 4:34 AM, Tauro, Riana wrote:
>
>
> On 10/12/2022 11:56 PM, Vinay Belgaumkar wrote:
>> GuC will set the min/max frequencies to theoretical max on
>> ATS-M. This will break kernel ABI, so limit min/max frequency
>> to RP0(platform max) instead.
>>
>> Also modify the SLPC selftest to update the min frequency
>> when we have a server part so that we can iterate between
>> platform min and max.
>>
>> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/selftest_slpc.c       | 40 +++++++++++++------
>>   drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c   | 29 ++++++++++++++
>>   .../gpu/drm/i915/gt/uc/intel_guc_slpc_types.h |  3 ++
>>   3 files changed, 60 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/selftest_slpc.c 
>> b/drivers/gpu/drm/i915/gt/selftest_slpc.c
>> index 4c6e9257e593..1f84362af737 100644
>> --- a/drivers/gpu/drm/i915/gt/selftest_slpc.c
>> +++ b/drivers/gpu/drm/i915/gt/selftest_slpc.c
>> @@ -234,6 +234,7 @@ static int run_test(struct intel_gt *gt, int 
>> test_type)
>>       enum intel_engine_id id;
>>       struct igt_spinner spin;
>>       u32 slpc_min_freq, slpc_max_freq;
>> +    u32 saved_min_freq;
>>       int err = 0;
>>         if (!intel_uc_uses_guc_slpc(&gt->uc))
>> @@ -252,20 +253,35 @@ static int run_test(struct intel_gt *gt, int 
>> test_type)
>>           return -EIO;
>>       }
>>   -    /*
>> -     * FIXME: With efficient frequency enabled, GuC can request
>> -     * frequencies higher than the SLPC max. While this is fixed
>> -     * in GuC, we level set these tests with RPn as min.
>> -     */
>> -    err = slpc_set_min_freq(slpc, slpc->min_freq);
>> -    if (err)
>> -        return err;
>> -
>>       if (slpc->min_freq == slpc->rp0_freq) {
> This has to be (slpc_min_freq == slpc_max_freq) instead of
> (slpc->min_freq == slpc->rp0_freq).
>
> Servers will have min/max softlimits clamped to RP0

Agree. will send out v2.

Thanks,

Vinay.

>
> Thanks
> Riana
>> -        pr_err("Min/Max are fused to the same value\n");
>> -        return -EINVAL;
>> +        /* Servers will have min/max clamped to RP0 */
>> +        if (slpc->min_is_rpmax) {
>> +            err = slpc_set_min_freq(slpc, slpc->min_freq);
>> +            if (err) {
>> +                pr_err("Unable to update min freq on server part");
>> +                return err;
>> +            }
>> +
>> +        } else {
>> +            pr_err("Min/Max are fused to the same value\n");
>> +            return -EINVAL;
>> +        }
>> +    } else {
>> +        /*
>> +         * FIXME: With efficient frequency enabled, GuC can request
>> +         * frequencies higher than the SLPC max. While this is fixed
>> +         * in GuC, we level set these tests with RPn as min.
>> +         */
>> +        err = slpc_set_min_freq(slpc, slpc->min_freq);
>> +        if (err)
>> +            return err;
>>       }
>>   +    saved_min_freq = slpc_min_freq;
>> +
>> +    /* New temp min freq = RPn */
>> +    slpc_min_freq = slpc->min_freq;
>> +
>>       intel_gt_pm_wait_for_idle(gt);
>>       intel_gt_pm_get(gt);
>>       for_each_engine(engine, gt, id) {
>> @@ -347,7 +363,7 @@ static int run_test(struct intel_gt *gt, int 
>> test_type)
>>         /* Restore min/max frequencies */
>>       slpc_set_max_freq(slpc, slpc_max_freq);
>> -    slpc_set_min_freq(slpc, slpc_min_freq);
>> +    slpc_set_min_freq(slpc, saved_min_freq);
>>         if (igt_flush_test(gt->i915))
>>           err = -EIO;
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c 
>> b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
>> index fdd895f73f9f..11613d373a49 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
>> @@ -263,6 +263,7 @@ int intel_guc_slpc_init(struct intel_guc_slpc *slpc)
>>         slpc->max_freq_softlimit = 0;
>>       slpc->min_freq_softlimit = 0;
>> +    slpc->min_is_rpmax = false;
>>         slpc->boost_freq = 0;
>>       atomic_set(&slpc->num_waiters, 0);
>> @@ -588,6 +589,31 @@ static int slpc_set_softlimits(struct 
>> intel_guc_slpc *slpc)
>>       return 0;
>>   }
>>   +static bool is_slpc_min_freq_rpmax(struct intel_guc_slpc *slpc)
>> +{
>> +    int slpc_min_freq;
>> +
>> +    if (intel_guc_slpc_get_min_freq(slpc, &slpc_min_freq))
>> +        return false;
>> +
>> +    if (slpc_min_freq > slpc->rp0_freq)
>> +        return true;
>> +    else
>> +        return false;
>> +}
>> +
>> +static void update_server_min_softlimit(struct intel_guc_slpc *slpc)
>> +{
>> +    /* For server parts, SLPC min will be at RPMax.
>> +     * Use min softlimit to clamp it to RP0 instead.
>> +     */
>> +    if (is_slpc_min_freq_rpmax(slpc) &&
>> +        !slpc->min_freq_softlimit) {
>> +        slpc->min_is_rpmax = true;
>> +        slpc->min_freq_softlimit = slpc->rp0_freq;
>> +    }
>> +}
>> +
>>   static int slpc_use_fused_rp0(struct intel_guc_slpc *slpc)
>>   {
>>       /* Force SLPC to used platform rp0 */
>> @@ -647,6 +673,9 @@ int intel_guc_slpc_enable(struct intel_guc_slpc 
>> *slpc)
>>         slpc_get_rp_values(slpc);
>>   +    /* Handle the case where min=max=RPmax */
>> +    update_server_min_softlimit(slpc);
>> +
>>       /* Set SLPC max limit to RP0 */
>>       ret = slpc_use_fused_rp0(slpc);
>>       if (unlikely(ret)) {
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc_types.h 
>> b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc_types.h
>> index 73d208123528..a6ef53b04e04 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc_types.h
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc_types.h
>> @@ -19,6 +19,9 @@ struct intel_guc_slpc {
>>       bool supported;
>>       bool selected;
>>   +    /* Indicates this is a server part */
>> +    bool min_is_rpmax;
>> +
>>       /* platform frequency limits */
>>       u32 min_freq;
>>       u32 rp0_freq;