Date:   Thu, 20 Jun 2019 13:58:32 +0530
From:   amasule@...eaurora.org
To:     Stanimir Varbanov <stanimir.varbanov@...aro.org>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, vgarodia@...eaurora.org
Subject: Re: [PATCH 3/5] media: venus: Update clock scaling

Hi Stan,

On 2019-06-17 14:28, Stanimir Varbanov wrote:
> Hi Aniket,
> 
> On 6/11/19 9:05 AM, Aniket Masule wrote:
>> Current clock scaling calculations are same for vpu4 and
>> previous versions. For vpu4, Clock scaling calculations
>> are updated with cycles/mb. This helps in getting precise
>> clock required.
>> 
>> Signed-off-by: Aniket Masule <amasule@...eaurora.org>
>> ---
>>  drivers/media/platform/qcom/venus/helpers.c | 88 
>> +++++++++++++++++++++++++++--
>>  1 file changed, 84 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/media/platform/qcom/venus/helpers.c 
>> b/drivers/media/platform/qcom/venus/helpers.c
>> index f7f724b..7bcc1e6 100644
>> --- a/drivers/media/platform/qcom/venus/helpers.c
>> +++ b/drivers/media/platform/qcom/venus/helpers.c
>> @@ -348,8 +348,9 @@ static u32 load_per_type(struct venus_core *core, 
>> u32 session_type)
>>  	return mbs_per_sec;
>>  }
>> 
>> -static int load_scale_clocks(struct venus_core *core)
>> +static int scale_clocks(struct venus_inst *inst)
>>  {
>> +	struct venus_core *core = inst->core;
>>  	const struct freq_tbl *table = core->res->freq_tbl;
>>  	unsigned int num_rows = core->res->freq_tbl_size;
>>  	unsigned long freq = table[0].freq;
>> @@ -398,6 +399,86 @@ static int load_scale_clocks(struct venus_core 
>> *core)
>>  	return ret;
>>  }
>> 
>> +static unsigned long calculate_inst_freq(struct venus_inst *inst)
>> +{
>> +	unsigned long vpp_cycles = 0;
>> +	u32 mbs_per_sec;
>> +
>> +	mbs_per_sec = load_per_instance(inst);
>> +	vpp_cycles = mbs_per_sec * inst->clk_data.codec_data->vpp_cycles;
>> +	/* 21 / 20 is overhead factor */
>> +	vpp_cycles += vpp_cycles / 20;
> 
> shouldn't you multiply by 21?
> 
Expansion of given expression results to the same.
>> +
>> +	return vpp_cycles;
> 
> It is not clear to me is that vpp_cycles or frequency (rate)? I just
> lost in dimensions used here.
> 
> If you return vpp_cycles could you rename the function name?
> 
Initial calculations included frequency (for bitrate based scaling), 
which I removed.
I will rename it calculate_inst_vpp_cycles for this patch.
>> +}
>> +
>> +static int scale_clocks_vpu4(struct venus_inst *inst)
> 
> does vpu4 equivalent to HFI_VERSION_4XX? If so could you rename 
> function
> to scale_clocks_v4.
> 
Sure Stan, I will rename it to scale_clocks_v4.
>> +{
>> +	struct venus_core *core = inst->core;
>> +	const struct freq_tbl *table = core->res->freq_tbl;
>> +	unsigned int num_rows = core->res->freq_tbl_size;
>> +
>> +	struct clk *clk = core->clks[0];
>> +	struct device *dev = core->dev;
>> +	unsigned int i;
>> +	unsigned long freq = 0, freq_core0 = 0, freq_core1 = 0;
>> +	int ret;
>> +
>> +	freq = calculate_inst_freq(inst);
>> +
>> +	if (freq > table[0].freq)
>> +		goto err;
>> +
>> +	for (i = 0; i < num_rows; i++) {
>> +		if (freq > table[i].freq)
>> +			break;
>> +		freq = table[i].freq;
>> +	}
>> +
>> +	inst->clk_data.freq = freq;
>> +
>> +	mutex_lock(&core->lock);
>> +	list_for_each_entry(inst, &core->instances, list) {
>> +		if (inst->clk_data.core_id == VIDC_CORE_ID_1) {
>> +			freq_core0 += inst->clk_data.freq;
>> +		} else if (inst->clk_data.core_id == VIDC_CORE_ID_2) {
>> +			freq_core1 += inst->clk_data.freq;
>> +		} else if (inst->clk_data.core_id == VIDC_CORE_ID_3) {
>> +			freq_core0 += inst->clk_data.freq;
>> +			freq_core1 += inst->clk_data.freq;
>> +		}
>> +	}
>> +	mutex_unlock(&core->lock);
>> +
>> +	freq = max(freq_core0, freq_core1);
> 
> hmm, this doesn't look right. core0 and core1 frequencies can be
> different why you get the bigger and set it on both?
> 
We can't set separate clocks to core0 and core1.
As per the design, we can set clocks to the branch only not the 
individual cores.
>> +
>> +	ret = clk_set_rate(clk, freq);
>> +	if (ret)
>> +		goto err;
>> +
>> +	ret = clk_set_rate(core->core0_clk, freq);
> 
> IMO this should set freq_core0
We need set max required frequency, due to the reason mentioned above.
> 
>> +	if (ret)
>> +		goto err;
>> +
>> +	ret = clk_set_rate(core->core1_clk, freq);
> 
> set freq_core1
> 
We need set max required frequency, due to the reason mentioned above.
>> +	if (ret)
>> +		goto err;
>> +
>> +	return 0;
>> +
>> +err:
>> +	dev_err(dev, "failed to set clock rate %lu (%d)\n", freq, ret);
>> +	return ret;
>> +}
>> +
>> +static int load_scale_clocks(struct venus_inst *inst)
>> +{
>> +	if (IS_V3(inst->core) || IS_V1(inst->core))
>> +		return scale_clocks(inst);
>> +	else
>> +		return scale_clocks_vpu4(inst);
> 
> could you reorder this to:
> 
> 	if (IS_V4())
> 		return scale_clocks_v4(inst);
> 
> 	return scale_clocks(inst);
> 
Yes Stan.
>> +}
>> +
>>  static void fill_buffer_desc(const struct venus_buffer *buf,
>>  			     struct hfi_buffer_desc *bd, bool response)
>>  {
>> @@ -1053,7 +1134,7 @@ void venus_helper_vb2_stop_streaming(struct 
>> vb2_queue *q)
>> 
>>  		venus_helper_free_dpb_bufs(inst);
>> 
>> -		load_scale_clocks(core);
>> +		load_scale_clocks(inst);
>>  		INIT_LIST_HEAD(&inst->registeredbufs);
>>  	}
>> 
>> @@ -1070,7 +1151,6 @@ void venus_helper_vb2_stop_streaming(struct 
>> vb2_queue *q)
>> 
>>  int venus_helper_vb2_start_streaming(struct venus_inst *inst)
>>  {
>> -	struct venus_core *core = inst->core;
>>  	int ret;
>> 
>>  	ret = intbufs_alloc(inst);
>> @@ -1081,7 +1161,7 @@ int venus_helper_vb2_start_streaming(struct 
>> venus_inst *inst)
>>  	if (ret)
>>  		goto err_bufs_free;
>> 
>> -	load_scale_clocks(core);
>> +	load_scale_clocks(inst);
>> 
>>  	ret = hfi_session_load_res(inst);
>>  	if (ret)
>> 

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