linux-kernel - Re: [PATCH v6 2/4] media: venus: Update clock scaling

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Message-ID: <c02c070d-7f22-88ba-d254-18951c34ce5e@linaro.org>
Date:   Mon, 29 Jul 2019 11:35:28 +0300
From:   Stanimir Varbanov <stanimir.varbanov@...aro.org>
To:     Aniket Masule <amasule@...eaurora.org>, linux-media@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        vgarodia@...eaurora.org
Subject: Re: [PATCH v6 2/4] media: venus: Update clock scaling

Hi Aniket,

On 7/22/19 12:07 PM, 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 | 91 +++++++++++++++++++++++++++--
>  1 file changed, 87 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/qcom/venus/helpers.c b/drivers/media/platform/qcom/venus/helpers.c
> index 7492373..2c976e4 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 +399,89 @@ static int load_scale_clocks(struct venus_core *core)
>  	return ret;
>  }
>  
> +static unsigned long calculate_vpp_freq(struct venus_inst *inst)
> +{
> +	unsigned long vpp_freq = 0;
> +	u32 mbs_per_sec;
> +
> +	mbs_per_sec = load_per_instance(inst);
> +	vpp_freq = mbs_per_sec * inst->clk_data.codec_freq_data->vpp_freq;
> +	/* 21 / 20 is overhead factor */
> +	vpp_freq += vpp_freq / 20;
> +
> +	return vpp_freq;
> +}
> +
> +static int scale_clocks_v4(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;
> +	struct clk *clk = core->clks[0];
> +	struct device *dev = core->dev;
> +	unsigned int i;
> +	unsigned long freq = 0, freq_core1 = 0, freq_core2 = 0;
> +	int ret;
> +
> +	freq = calculate_vpp_freq(inst);
> +
> +	if (freq > table[0].freq)
> +		dev_warn(dev, "HW is overloaded, needed: %lu max: %lu\n",
> +			 freq, table[0].freq);
> +

...

> +	for (i = 0; i < num_rows; i++) {
> +		if (freq > table[i].freq)
> +			break;
> +		freq = table[i].freq;
> +	}

The above code snippet will select the biggest table[0].freq always.
Infact do we need to "normalize" the calculated freq to the table of
possible clock rates? I think tjat should be made after sum all needed
frequencies for all cores.

> +
> +	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_core1 += inst->clk_data.freq;
> +		} else if (inst->clk_data.core_id == VIDC_CORE_ID_2) {
> +			freq_core2 += inst->clk_data.freq;
> +		} else if (inst->clk_data.core_id == VIDC_CORE_ID_3) {
> +			freq_core1 += inst->clk_data.freq;
> +			freq_core2 += inst->clk_data.freq;
> +		}
> +	}
> +	mutex_unlock(&core->lock);
> +
> +	freq = max(freq_core1, freq_core2);
> +
> +	ret = clk_set_rate(clk, freq);
> +	if (ret)
> +		goto err;
> +
> +	ret = clk_set_rate(core->core0_clk, freq);
> +	if (ret)
> +		goto err;
> +
> +	ret = clk_set_rate(core->core1_clk, freq);
> +	if (ret)
> +		goto err;

This is duplicated in both scale_clocks and scale_clocks_v4, and could
be a common function.

> +
> +	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_V4(inst->core))
> +		return scale_clocks_v4(inst);
> +
> +	if (inst->state == INST_START)
> +		return 0;

I'm still not sure about this check of the instance state.

If we look into load_per_instance() it already doing similar check :

!(inst->state >= INST_INIT && inst->state < INST_STOP)


> +
> +	return scale_clocks(inst);
> +}
> +
>  static void fill_buffer_desc(const struct venus_buffer *buf,
>  			     struct hfi_buffer_desc *bd, bool response)
>  {
> @@ -1053,7 +1137,7 @@ 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 +1154,6 @@ 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 +1164,7 @@ 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)
> 

-- 
regards,
Stan