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 <amas...@codeaurora.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.

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