Re: [PATCH 07/14] drm/i915/guc/slpc: Add methods to set min/max frequency

["Belgaumkar, Vinay" <vinay.belgaumkar@intel.com>]

On 7/21/2021 10:42 AM, Michal Wajdeczko wrote:
> 
> 
> On 21.07.2021 18:11, Vinay Belgaumkar wrote:
>> Add param set h2g helpers to set the min and max frequencies
>> for use by SLPC.
>>
>> v2: Address review comments (Michal W)
>>
>> Signed-off-by: Sundaresan Sujaritha <sujaritha.sundaresan@intel.com>
>> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c | 84 +++++++++++++++++++++
>>   drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.h |  2 +
>>   2 files changed, 86 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 48db2a8f67d1..b40c39ba4049 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
>> @@ -109,6 +109,18 @@ static u32 slpc_get_state(struct intel_guc_slpc *slpc)
>>   	return data->header.global_state;
>>   }
>>   
>> +static int guc_action_slpc_set_param(struct intel_guc *guc, u8 id, u32 value)
>> +{
>> +	u32 request[] = {
>> +		INTEL_GUC_ACTION_SLPC_REQUEST,
>> + 		SLPC_EVENT(SLPC_EVENT_PARAMETER_SET, 2),
>> +		id,
>> +		value,
>> +	};
>> +
>> + 	return intel_guc_send(guc, request, ARRAY_SIZE(request));
> 
> beware of possible non-zero data0 returned by guc_send()

Ok, added -EPROTO check.
> 
>> +}
>> +
>>   static bool slpc_is_running(struct intel_guc_slpc *slpc)
>>   {
>>   	return (slpc_get_state(slpc) == SLPC_GLOBAL_STATE_RUNNING);
>> @@ -143,6 +155,15 @@ static int slpc_query_task_state(struct intel_guc_slpc *slpc)
>>   	return ret;
>>   }
>>   
>> +static int slpc_set_param(struct intel_guc_slpc *slpc, u8 id, u32 value)
>> +{
>> +	struct intel_guc *guc = slpc_to_guc(slpc);
>> +
>> +	GEM_BUG_ON(id >= SLPC_MAX_PARAM);
>> +
>> +	return guc_action_slpc_set_param(guc, id, value);
>> +}
>> +
>>   static const char *slpc_state_string(struct intel_guc_slpc *slpc)
>>   {
>>   	const char *str = NULL;
>> @@ -238,6 +259,69 @@ u32 slpc_decode_max_freq(struct intel_guc_slpc *slpc)
>>   		GT_FREQUENCY_MULTIPLIER, GEN9_FREQ_SCALER);
>>   }
>>   
>> +/**
>> + * intel_guc_slpc_set_max_freq() - Set max frequency limit for SLPC.
>> + * @slpc: pointer to intel_guc_slpc.
>> + * @val: frequency (MHz)
>> + *
>> + * This function will invoke GuC SLPC action to update the max frequency
>> + * limit for unslice.
>> + *
>> + * Return: 0 on success, non-zero error code on failure.
>> + */
>> +int intel_guc_slpc_set_max_freq(struct intel_guc_slpc *slpc, u32 val)
>> +{
>> +	int ret;
>> +	struct drm_i915_private *i915 = slpc_to_i915(slpc);
>> +	intel_wakeref_t wakeref;
> 
> nit: move "ret" as last

ok.

> 
>> +
>> +	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
>> +		ret = slpc_set_param(slpc,
>> +			       SLPC_PARAM_GLOBAL_MAX_GT_UNSLICE_FREQ_MHZ,
>> +			       val);
>> +		if (ret) {
>> +			drm_err(&i915->drm,
>> +				"Set max frequency unslice returned (%pe)\n", ERR_PTR(ret));
>> +			/* Return standardized err code for sysfs */
>> +			ret = -EIO;
> 
> maybe caller (hook in sysfs) can sanitize this error ?

Caller will then need to check the error type - something like-

if (err) {
     if (err != -EINVAL)
         return -EIO;
}

Seems cleaner to return specific error type from here instead.
Anything other than -EINVAL or -EIO causes garbage in sysfs output.

Thanks,
Vinay.

> 
> Michal
> 
>> +		}
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * intel_guc_slpc_set_min_freq() - Set min frequency limit for SLPC.
>> + * @slpc: pointer to intel_guc_slpc.
>> + * @val: frequency (MHz)
>> + *
>> + * This function will invoke GuC SLPC action to update the min unslice
>> + * frequency.
>> + *
>> + * Return: 0 on success, non-zero error code on failure.
>> + */
>> +int intel_guc_slpc_set_min_freq(struct intel_guc_slpc *slpc, u32 val)
>> +{
>> +	int ret;
>> +	struct intel_guc *guc = slpc_to_guc(slpc);
>> +	struct drm_i915_private *i915 = guc_to_gt(guc)->i915;
>> +	intel_wakeref_t wakeref;
>> +
>> +	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
>> +		ret = slpc_set_param(slpc,
>> +			       SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
>> +			       val);
>> +		if (ret) {
>> +			drm_err(&i915->drm,
>> +				"Set min frequency for unslice returned (%pe)\n", ERR_PTR(ret));
>> +			/* Return standardized err code for sysfs */
>> +			ret = -EIO;
>> +		}
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>>   /*
>>    * intel_guc_slpc_enable() - Start SLPC
>>    * @slpc: pointer to intel_guc_slpc.
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.h
>> index f02249ff5f1b..3a1a7eaafc12 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.h
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.h
>> @@ -30,5 +30,7 @@ void intel_guc_slpc_init_early(struct intel_guc_slpc *slpc);
>>   int intel_guc_slpc_init(struct intel_guc_slpc *slpc);
>>   int intel_guc_slpc_enable(struct intel_guc_slpc *slpc);
>>   void intel_guc_slpc_fini(struct intel_guc_slpc *slpc);
>> +int intel_guc_slpc_set_max_freq(struct intel_guc_slpc *slpc, u32 val);
>> +int intel_guc_slpc_set_min_freq(struct intel_guc_slpc *slpc, u32 val);
>>   
>>   #endif
>>