Re: [Intel-gfx] [PATCH 11/14] drm/i915/guc/slpc: Cache platform frequency limits

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 28.07.2021 23:11, Vinay Belgaumkar wrote:
> Cache rp0, rp1 and rpn platform limits into SLPC structure
> for range checking while setting min/max frequencies.
> 
> Also add "soft" limits which keep track of frequency changes
> made from userland. These are initially set to platform min
> and max.
> 
> v2: Address review comments (Michal W)
> v3: Formatting (Michal W)
> v4: Add separate function to parse rp values (Michal W)
> v5: Perform range checking for set min/max (Michal W)
> 
> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c   | 115 ++++++++++++++++++
>  .../gpu/drm/i915/gt/uc/intel_guc_slpc_types.h |   9 ++
>  drivers/gpu/drm/i915/i915_reg.h               |   3 +
>  3 files changed, 127 insertions(+)
> 
> 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 742918875593..bfd5fb0751fd 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
> @@ -94,6 +94,9 @@ static int slpc_shared_data_init(struct intel_guc_slpc *slpc)
>  		return err;
>  	}
>  
> +	slpc->max_freq_softlimit = 0;
> +	slpc->min_freq_softlimit = 0;

shouldn't this be in intel_guc_slpc_init() ?

> +
>  	return err;
>  }
>  
> @@ -124,6 +127,18 @@ static int guc_action_slpc_set_param(struct intel_guc *guc, u8 id, u32 value)
>  	return ret > 0 ? -EPROTO : ret;
>  }
>  
> +static int guc_action_slpc_unset_param(struct intel_guc *guc, u8 id)
> +{
> +	u32 request[] = {
> +		GUC_ACTION_HOST2GUC_PC_SLPC_REQUEST,
> +		SLPC_EVENT(SLPC_EVENT_PARAMETER_UNSET, 2),
> +		id,
> +	};
> +
> +	return intel_guc_send(guc, request, ARRAY_SIZE(request));
> +}
> +
> +
>  static bool slpc_is_running(struct intel_guc_slpc *slpc)
>  {
>  	return slpc_get_state(slpc) == SLPC_GLOBAL_STATE_RUNNING;
> @@ -177,6 +192,16 @@ static int slpc_set_param(struct intel_guc_slpc *slpc, u8 id, u32 value)
>  	return ret;
>  }
>  
> +static int slpc_unset_param(struct intel_guc_slpc *slpc,
> +				u8 id)
> +{
> +	struct intel_guc *guc = slpc_to_guc(slpc);
> +
> +	GEM_BUG_ON(id >= SLPC_MAX_PARAM);
> +
> +	return guc_action_slpc_unset_param(guc, id);
> +}
> +
>  static const char *slpc_global_state_to_string(enum slpc_global_state state)
>  {
>  	switch (state) {
> @@ -307,6 +332,11 @@ int intel_guc_slpc_set_max_freq(struct intel_guc_slpc *slpc, u32 val)
>  	intel_wakeref_t wakeref;
>  	int ret;
>  
> +	if ((val < slpc->min_freq) ||
> +	    (val > slpc->rp0_freq) ||
> +	    (val < slpc->min_freq_softlimit))
> +		return -EINVAL;
> +
>  	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
>  		ret = slpc_set_param(slpc,
>  			       SLPC_PARAM_GLOBAL_MAX_GT_UNSLICE_FREQ_MHZ,
> @@ -317,6 +347,8 @@ int intel_guc_slpc_set_max_freq(struct intel_guc_slpc *slpc, u32 val)
>  			ret = -EIO;
>  	}
>  
> +	slpc->max_freq_softlimit = val;
> +
>  	return ret;
>  }
>  
> @@ -363,6 +395,11 @@ int intel_guc_slpc_set_min_freq(struct intel_guc_slpc *slpc, u32 val)
>  	intel_wakeref_t wakeref;
>  	int ret;
>  
> +	if ((val < slpc->min_freq) ||
> +	    (val > slpc->rp0_freq) ||
> +	    (val > slpc->max_freq_softlimit))
> +		return -EINVAL;
> +
>  	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
>  		ret = slpc_set_param(slpc,
>  			       SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
> @@ -373,6 +410,8 @@ int intel_guc_slpc_set_min_freq(struct intel_guc_slpc *slpc, u32 val)
>  			ret = -EIO;
>  	}
>  
> +	slpc->min_freq_softlimit = val;
> +
>  	return ret;
>  }
>  
> @@ -418,6 +457,71 @@ void intel_guc_pm_intrmsk_enable(struct intel_gt *gt)
>  			   GEN6_PMINTRMSK, pm_intrmsk_mbz, 0);
>  }
>  
> +static int slpc_set_softlimits(struct intel_guc_slpc *slpc)
> +{
> +	int ret = 0;
> +
> +	/*
> +	 * Softlimits are initially equivalent to platform limits
> +	 * unless they have deviated from defaults, in which case,
> +	 * we retain the values and set min/max accordingly.
> +	 */
> +	if (!slpc->max_freq_softlimit)
> +		slpc->max_freq_softlimit = slpc->rp0_freq;
> +	else if (slpc->max_freq_softlimit != slpc->rp0_freq)
> +		ret = intel_guc_slpc_set_max_freq(slpc,
> +					slpc->max_freq_softlimit);

if this fails, shouldn't we reset max_freq_softlimit to platform limit ?
otherwise we could be with some potentially bad value forever

> +
> +	if (!slpc->min_freq_softlimit)
> +		slpc->min_freq_softlimit = slpc->min_freq;
> +	else if (slpc->min_freq_softlimit != slpc->min_freq)
> +		ret = intel_guc_slpc_set_min_freq(slpc,
> +					slpc->min_freq_softlimit);

similar here

> +
> +	return ret;
> +}
> +
> +static void intel_guc_slpc_ignore_eff_freq(struct intel_guc_slpc *slpc, bool ignore)

static functions don't need "intel_guc" prefix

slpc_ignore_eff_freq

> +{
> +	/* A failure here does not affect the algorithm in a fatal way */
> +	if (ignore) {
> +		slpc_set_param(slpc,
> +		   SLPC_PARAM_IGNORE_EFFICIENT_FREQUENCY,
> +		   ignore);
> +		slpc_set_param(slpc,
> +		   SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
> +		   slpc->min_freq);
> +	} else {
> +		slpc_unset_param(slpc,
> +		   SLPC_PARAM_IGNORE_EFFICIENT_FREQUENCY);
> +		slpc_unset_param(slpc,
> +		   SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ);

indents are likely wrong

> +	}
> +}
> +
> +static void intel_guc_slpc_use_fused_rp0(struct intel_guc_slpc *slpc)

slpc_use_fused_rp0

> +{
> +	/* Force SLPC to used platform rp0 */
> +	slpc_set_param(slpc,
> +			SLPC_PARAM_GLOBAL_MAX_GT_UNSLICE_FREQ_MHZ,
> +			slpc->rp0_freq);
> +}
> +
> +static void slpc_get_rp_values(struct intel_guc_slpc *slpc)
> +{
> +	u32 rp_state_cap;
> +
> +	rp_state_cap = intel_uncore_read(slpc_to_gt(slpc)->uncore,
> +					 GEN6_RP_STATE_CAP);
> +
> +	slpc->rp0_freq = REG_FIELD_GET(RP0_CAP_MASK, rp_state_cap) *
> +					GT_FREQUENCY_MULTIPLIER;
> +	slpc->rp1_freq = REG_FIELD_GET(RP1_CAP_MASK, rp_state_cap) *
> +					GT_FREQUENCY_MULTIPLIER;
> +	slpc->min_freq = REG_FIELD_GET(RPN_CAP_MASK, rp_state_cap) *
> +					GT_FREQUENCY_MULTIPLIER;
> +}
> +
>  /*
>   * intel_guc_slpc_enable() - Start SLPC
>   * @slpc: pointer to intel_guc_slpc.
> @@ -453,6 +557,17 @@ int intel_guc_slpc_enable(struct intel_guc_slpc *slpc)
>  
>  	intel_guc_pm_intrmsk_enable(&i915->gt);
>  
> +	slpc_get_rp_values(slpc);
> +
> +	/* Ignore efficient freq and set min/max to platform min/max */
> +	intel_guc_slpc_ignore_eff_freq(slpc, true);
> +	intel_guc_slpc_use_fused_rp0(slpc);
> +
> +	ret = slpc_set_softlimits(slpc);
> +	if (ret)
> +		drm_err(&i915->drm, "Failed to set SLPC softlimits (%pe)\n",
> +					ERR_PTR(ret));

indent ?

> +
>  	return 0;
>  }
>  
> 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 3cefe19b17b2..41d13527666f 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
> @@ -15,6 +15,15 @@ struct intel_guc_slpc {
>  	struct slpc_shared_data *vaddr;
>  	bool supported;
>  	bool selected;
> +
> +	/* platform frequency limits */
> +	u32 min_freq;
> +	u32 rp0_freq;
> +	u32 rp1_freq;
> +
> +	/* frequency softlimits */
> +	u32 min_freq_softlimit;
> +	u32 max_freq_softlimit;
>  };
>  
>  #endif
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 5603377e06ca..f3a445f79a36 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4109,6 +4109,9 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
>  #define BXT_GT_PERF_STATUS      _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x7070)
>  #define GEN6_RP_STATE_LIMITS	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5994)
>  #define GEN6_RP_STATE_CAP	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5998)
> +#define   RP0_CAP_MASK		REG_GENMASK(7, 0)
> +#define   RP1_CAP_MASK		REG_GENMASK(15, 8)
> +#define   RPN_CAP_MASK		REG_GENMASK(23, 16)
>  #define BXT_RP_STATE_CAP        _MMIO(0x138170)
>  #define GEN9_RP_STATE_LIMITS	_MMIO(0x138148)
>  
> 
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