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

[amasule]

Hi Stan,

On 2019-07-29 14:05, Stanimir Varbanov wrote:
> 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@xxxxxxxxxxxxxx>
> > ---
> >  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.
Will correct this. Normalizing after sum of all needed frequencies
would be more precise.
> > +
> > +	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.
I will move this to 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)
This check would just make sure instance state for scaling,
not a mandatory check. I can remove the check.
> > +
> > +	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,
Aniket