Subject: Re: [PATCH v5 3/3] PM / AVS: SVS: Introduce SVS engine

From: Roger Lu <[email-masked]>
Date: Fri, 27 Dec 2019 15:14:49 +0800

Dear Pi-Hsun,

Sorry for the late reply.

On Thu, 2019-11-14 at 15:41 +0800, Pi-Hsun Shih wrote:
> Hi Roger,
> 
> On Fri, Sep 6, 2019 at 6:06 PM Roger Lu <[email-masked]> wrote:
> >
> > The SVS (Smart Voltage Scaling) engine is a piece of hardware which is
> > used to calculate optimized voltage values of several power domains, e.g.
> > CPU/GPU/CCI, according to chip process corner, temperatures, and other
> > factors. Then DVFS driver could apply those optimized voltage values to
> > reduce power consumption.
> >
> > Signed-off-by: Roger Lu <[email-masked]>
> > ---
> >  drivers/power/avs/Kconfig     |   10 +
> >  drivers/power/avs/Makefile    |    1 +
> >  drivers/power/avs/mtk_svs.c   | 2075 +++++++++++++++++++++++++++++++++
> >  include/linux/power/mtk_svs.h |   23 +
> >  4 files changed, 2109 insertions(+)
> >  create mode 100644 drivers/power/avs/mtk_svs.c
> >  create mode 100644 include/linux/power/mtk_svs.h
> >
> > [...]
> > diff --git a/drivers/power/avs/mtk_svs.c b/drivers/power/avs/mtk_svs.c
> > new file mode 100644
> > index 000000000000..78ec93c3a4a5
> > --- /dev/null
> > +++ b/drivers/power/avs/mtk_svs.c
> > [...]
> > +static int svs_set_volts(struct svs_bank *svsb, bool force_update)
> > +{
> > +       u32 i, svsb_volt, opp_volt, low_temp_offset = 0;
> > +       int zone_temp, ret;
> > +
> > +       mutex_lock(&svsb->lock);
> > +
> > +       /* If bank is suspended, it means init02 voltage is applied.
> > +        * Don't need to update opp voltage anymore.
> > +        */
> > +       if (svsb->suspended && !force_update) {
> > +               pr_notice("%s: bank is suspended\n", svsb->name);
> > +               mutex_unlock(&svsb->lock);
> > +               return -EPERM;
> > +       }
> > +
> > +       /* get thermal effect */
> > +       if (svsb->phase == SVS_PHASE_MON) {
> > +               if (svsb->svs_temp > svsb->upper_temp_bound &&
> > +                   svsb->svs_temp < svsb->lower_temp_bound) {
> > +                       pr_err("%s: svs_temp is abnormal (0x%x)?\n",
> > +                              svsb->name, svsb->svs_temp);
> > +                       mutex_unlock(&svsb->lock);
> > +                       return -EINVAL;
> > +               }
> > +
> > +               ret = svs_get_zone_temperature(svsb, &zone_temp);
> > +               if (ret) {
> > +                       pr_err("%s: cannot get zone \"%s\" temperature\n",
> > +                              svsb->name, svsb->zone_name);
> > +                       pr_err("%s: add low_temp_offset = %u\n",
> > +                              svsb->name, svsb->low_temp_offset);
> > +                       zone_temp = svsb->low_temp_threashold;
> > +               }
> > +
> > +               if (zone_temp <= svsb->low_temp_threashold)
> > +                       low_temp_offset = svsb->low_temp_offset;
> > +       }
> > +
> > +       /* vmin <= svsb_volt (opp_volt) <= signed-off voltage */
> > +       for (i = 0; i < svsb->opp_count; i++) {
> > +               if (svsb->phase == SVS_PHASE_MON) {
> > +                       svsb_volt = max((svsb->volts[i] + svsb->volt_offset +
> > +                                        low_temp_offset), svsb->vmin);
> > +                       opp_volt = svs_volt_to_opp_volt(svsb_volt,
> > +                                                       svsb->volt_step,
> > +                                                       svsb->volt_base);
> > +               } else if (svsb->phase == SVS_PHASE_INIT02) {
> > +                       svsb_volt = max((svsb->init02_volts[i] +
> > +                                        svsb->volt_offset), svsb->vmin);
> > +                       opp_volt = svs_volt_to_opp_volt(svsb_volt,
> > +                                                       svsb->volt_step,
> > +                                                       svsb->volt_base);
> > +               } else if (svsb->phase == SVS_PHASE_ERROR) {
> > +                       opp_volt = svsb->opp_volts[i];
> > +               } else {
> > +                       pr_err("%s: unknown phase: %u?\n",
> > +                              svsb->name, svsb->phase);
> > +                       mutex_unlock(&svsb->lock);
> > +                       return -EINVAL;
> > +               }
> > +
> > +               opp_volt = min(opp_volt, svsb->opp_volts[i]);
> > +               ret = dev_pm_opp_adjust_voltage(svsb->dev, svsb->opp_freqs[i],
> > +                                               opp_volt);
> 
> The version of this function in opp tree
> (https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git/commit/?h=opp/linux-next&id=25cb20a212a1f989385dfe23230817e69c62bee5)
> has a different function signature, so this should be changed too.

Sure. I'll update it in the next patch.

> 
> > +               if (ret) {
> > +                       pr_err("%s: set voltage failed: %d\n", svsb->name, ret);
> > +                       mutex_unlock(&svsb->lock);
> > +                       return ret;
> > +               }
> > +       }
> > +
> > +       mutex_unlock(&svsb->lock);
> > +
> > +       return 0;
> > +}
> > +
> > [...]
> > +static int svs_init01(struct mtk_svs *svs)
> > +{
> > +       const struct svs_platform *svsp = svs->platform;
> > +       struct svs_bank *svsb;
> > +       struct pm_qos_request qos_request = { {0} };
> > +       unsigned long flags, time_left;
> > +       bool search_done;
> > +       int ret = -EINVAL;
> > +       u32 opp_freqs, opp_vboot, buck_volt, idx, i;
> > +
> > +       /* Let CPUs leave idle-off state for initializing svs_init01. */
> > +       pm_qos_add_request(&qos_request, PM_QOS_CPU_DMA_LATENCY, 0);
> > +
> > +       /* Sometimes two svs_bank use the same buck.
> > +        * Therefore, we set each svs_bank to vboot voltage first.
> > +        */
> > +       for (idx = 0; idx < svsp->bank_num; idx++) {
> > +               svsb = &svsp->banks[idx];
> > +               search_done = false;
> > +
> > +               if (!svsb->init01_support)
> > +                       continue;
> > +
> > +               ret = regulator_set_mode(svsb->buck, REGULATOR_MODE_FAST);
> > +               if (ret)
> > +                       pr_notice("%s: fail to set fast mode: %d\n",
> > +                                 svsb->name, ret);
> > +
> > +               if (svsb->mtcmos_request) {
> > +                       ret = regulator_enable(svsb->buck);
> > +                       if (ret) {
> > +                               pr_err("%s: fail to enable %s power: %d\n",
> > +                                      svsb->name, svsb->buck_name, ret);
> > +                               goto init01_finish;
> > +                       }
> > +
> > +                       ret = dev_pm_domain_attach(svsb->dev, false);
> > +                       if (ret) {
> > +                               pr_err("%s: attach pm domain fail: %d\n",
> > +                                      svsb->name, ret);
> > +                               goto init01_finish;
> > +                       }
> > +
> > +                       pm_runtime_enable(svsb->dev);
> > +                       ret = pm_runtime_get_sync(svsb->dev);
> > +                       if (ret < 0) {
> > +                               pr_err("%s: turn mtcmos on fail: %d\n",
> > +                                      svsb->name, ret);
> > +                               goto init01_finish;
> > +                       }
> > +               }
> > +
> > +               /* Find the fastest freq that can be run at vboot and
> > +                * fix to that freq until svs_init01 is done.
> > +                */
> > +               opp_vboot = svs_volt_to_opp_volt(svsb->vboot,
> > +                                                svsb->volt_step,
> > +                                                svsb->volt_base);
> > +
> > +               for (i = 0; i < svsb->opp_count; i++) {
> > +                       opp_freqs = svsb->opp_freqs[i];
> > +                       if (!search_done && svsb->opp_volts[i] <= opp_vboot) {
> > +                               ret = dev_pm_opp_adjust_voltage(svsb->dev,
> > +                                                               opp_freqs,
> > +                                                               opp_vboot);
> 
> Same here.

Sure. I'll update it in the next patch.

> 
> > +                               if (ret) {
> > +                                       pr_err("%s: set voltage failed: %d\n",
> > +                                              svsb->name, ret);
> > +                                       goto init01_finish;
> > +                               }
> > +
> > +                               search_done = true;
> > +                       } else {
> > +                               dev_pm_opp_disable(svsb->dev,
> > +                                                  svsb->opp_freqs[i]);
> > +                       }
> > +               }
> > +       }
> > +
> > +       for (idx = 0; idx < svsp->bank_num; idx++) {
> > +               svsb = &svsp->banks[idx];
> > +               svs->bank = svsb;
> > +
> > +               if (!svsb->init01_support)
> > +                       continue;
> > +
> > +               opp_vboot = svs_volt_to_opp_volt(svsb->vboot,
> > +                                                svsb->volt_step,
> > +                                                svsb->volt_base);
> > +
> > +               buck_volt = regulator_get_voltage(svsb->buck);
> > +               if (buck_volt != opp_vboot) {
> > +                       pr_err("%s: buck voltage: %u, expected vboot: %u\n",
> > +                              svsb->name, buck_volt, opp_vboot);
> > +                       ret = -EPERM;
> > +                       goto init01_finish;
> > +               }
> > +
> > +               init_completion(&svsb->init_completion);
> > +               flags = claim_mtk_svs_lock();
> > +               svs_set_phase(svs, SVS_PHASE_INIT01);
> > +               release_mtk_svs_lock(flags);
> > +               time_left =
> > +                       wait_for_completion_timeout(&svsb->init_completion,
> > +                                                   msecs_to_jiffies(2000));
> > +               if (time_left == 0) {
> > +                       pr_err("%s: init01 completion timeout\n", svsb->name);
> > +                       ret = -EBUSY;
> > +                       goto init01_finish;
> > +               }
> > +       }
> > +
> > +init01_finish:
> > +       for (idx = 0; idx < svsp->bank_num; idx++) {
> > +               svsb = &svsp->banks[idx];
> > +
> > +               if (!svsb->init01_support)
> > +                       continue;
> > +
> > +               for (i = 0; i < svsb->opp_count; i++)
> > +                       dev_pm_opp_enable(svsb->dev, svsb->opp_freqs[i]);
> > +
> > +               if (regulator_set_mode(svsb->buck, REGULATOR_MODE_NORMAL))
> > +                       pr_notice("%s: fail to set normal mode: %d\n",
> > +                                 svsb->name, ret);
> > +
> > +               if (svsb->mtcmos_request) {
> > +                       if (pm_runtime_put_sync(svsb->dev))
> > +                               pr_err("%s: turn mtcmos off fail: %d\n",
> > +                                      svsb->name, ret);
> > +                       pm_runtime_disable(svsb->dev);
> > +                       dev_pm_domain_detach(svsb->dev, 0);
> > +                       if (regulator_disable(svsb->buck))
> > +                               pr_err("%s: fail to disable %s power: %d\n",
> > +                                      svsb->name, svsb->buck_name, ret);
> > +               }
> > +       }
> > +
> > +       pm_qos_remove_request(&qos_request);
> > +
> > +       return ret;
> > +}
> > +
> > [...]
> 
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