Re: [PATCH v3 12/17] media: venus: core: Add support for opp tables/perf voting

Rajendra Nayak
2020-04-29T15:10:52Z

Hey Stan,

On 4/29/2020 8:06 PM, Stanimir Varbanov wrote:
> Hi Rajendra,
>
> Thanks for the patch!
>
[]..

>> #include <linux/pm_runtime.h>
>> #include <media/videobuf2-v4l2.h>
>> #include <media/v4l2-mem2mem.h>
>> @@ -214,6 +215,20 @@ static int venus_probe(struct platform_device *pdev)
>> if (!core->pm_ops)
>> return -ENODEV;
>>
>> + core->opp_table = dev_pm_opp_set_clkname(dev, "core");
>
> Should we set opp clkname if opp_of_add_table fails? We have platforms
> which don't have opp tables in Venus DT node. We have to be backward
> compatible for them.

so the way its designed, you are expected to call dev_pm_opp_set_clkname()
*before* adding any OPPs from the OPP table.
As for backward compatibility its already handled by the OPP core now [1]
which makes sure dev_pm_opp_set_rate() is equivalent to a clk_set_rate()
in case of a missing OPP table.

>> + if (IS_ERR(core->opp_table))
>> + return PTR_ERR(core->opp_table);
>> +
>> + if (core->res->opp_pmdomain) {
>> + ret = dev_pm_opp_of_add_table(dev);
>> + if (!ret) {
>> + core->has_opp_table = true;
>> + } else if (ret != -ENODEV) {
>
> Is it possible dev_pm_opp_of_add_table() to return EPROBE_DEFER?

Nope, it does not, I had checked.

>> + dev_err(dev, "Invalid OPP table in Device tree\n");
>
> ... if so, please drop dev_err.
>
>> + return ret;
>> + }
>> + }
[]..

>> --- a/drivers/media/platform/qcom/venus/pm_helpers.c
>> +++ b/drivers/media/platform/qcom/venus/pm_helpers.c
>> @@ -9,6 +9,7 @@
>> #include <linux/iopoll.h>
>> #include <linux/kernel.h>
>> #include <linux/pm_domain.h>
>> +#include <linux/pm_opp.h>
>> #include <linux/pm_runtime.h>
>> #include <linux/types.h>
>> #include <media/v4l2-mem2mem.h>
>> @@ -66,10 +67,9 @@ static void core_clks_disable(struct venus_core *core)
>>
>> static int core_clks_set_rate(struct venus_core *core, unsigned long freq)
>> {
>> - struct clk *clk = core->clks[0];
>> int ret;
>>
>> - ret = clk_set_rate(clk, freq);
>> + ret = dev_pm_opp_set_rate(core->dev, freq);
>
> Is this will work for legacy platforms without OPP tables?

yes, see [1] which is already merged in mainline.

>
> Also what about the other clocks (vicodec0,1) in this function.

We continue to use clk_set_rate() for those. The performance state
is associated with only the core clk.

>> if (ret)
>> return ret;
>>
>> @@ -740,13 +740,15 @@ static int venc_power_v4(struct device *dev, int on)
>>
>> static int vcodec_domains_get(struct device *dev)
>> {
>> + struct opp_table *opp_table;
>> + struct device **opp_virt_dev;
>> struct venus_core *core = dev_get_drvdata(dev);
>> const struct venus_resources *res = core->res;
>> struct device *pd;
>> unsigned int i;
>>
>> if (!res->vcodec_pmdomains_num)
>> - return -ENODEV;
>> + goto skip_pmdomains;
>>
>> for (i = 0; i < res->vcodec_pmdomains_num; i++) {
>> pd = dev_pm_domain_attach_by_name(dev,
>> @@ -763,6 +765,24 @@ static int vcodec_domains_get(struct device *dev)
>> if (!core->pd_dl_venus)
>> return -ENODEV;
>>
>> +skip_pmdomains:
>> + if (!res->opp_pmdomain || !core->has_opp_table)
>> + return 0;
>> +
>> + /* Attach the power domain for setting performance state */
>> + opp_table = dev_pm_opp_attach_genpd(dev, res->opp_pmdomain, &opp_virt_dev);
>> + if (IS_ERR(opp_table)) {
>> + return PTR_ERR(opp_table);
>> + } else if (opp_virt_dev) {
>> + core->opp_pmdomain = *opp_virt_dev;
>> + core->opp_dl_venus = device_link_add(dev, core->opp_pmdomain,
>> + DL_FLAG_RPM_ACTIVE |
>> + DL_FLAG_PM_RUNTIME |
>> + DL_FLAG_STATELESS);
>> + if (!core->opp_dl_venus)
>> + return -ENODEV;
>
> I think as you return ENODEV you have to detach opp domain here because
> vcodec_domains_put() is not called in error path.

Ok, I'll fix that up.

Thanks for the review.

[1] https://lkml.org/lkml/2020/4/8/413