Re: [PATCH v6 51/52] PM / devfreq: tegra30: Support interconnect and OPPs from device-tree

Hi Dmitry,

On Mon, Oct 26, 2020 at 7:22 AM Dmitry Osipenko digetx@gmail.com wrote:

This patch moves ACTMON driver away from generating OPP table by itself, transitioning it to use the table which comes from device-tree. This change breaks compatibility with older device-trees in order to bring support for the interconnect framework to the driver. This is a mandatory change which needs to be done in order to implement interconnect-based memory DVFS. Users of legacy device-trees will get a message telling that theirs DT needs to be upgraded. Now ACTMON issues memory bandwidth request using dev_pm_opp_set_bw(), instead of driving EMC clock rate directly.

Tested-by: Peter Geis pgwipeout@gmail.com Tested-by: Nicolas Chauvet kwizart@gmail.com Signed-off-by: Dmitry Osipenko digetx@gmail.com

---

drivers/devfreq/tegra30-devfreq.c | 91 ++++++++++++++++--------------- 1 file changed, 48 insertions(+), 43 deletions(-)

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c index 3f732ab53573..1b0b91a71886 100644 --- a/drivers/devfreq/tegra30-devfreq.c +++ b/drivers/devfreq/tegra30-devfreq.c @@ -19,6 +19,8 @@ #include <linux/reset.h> #include <linux/workqueue.h>

+#include <soc/tegra/fuse.h>

#include "governor.h"

#define ACTMON_GLB_STATUS 0x0 @@ -155,6 +157,7 @@ struct tegra_devfreq_device {

struct tegra_devfreq { struct devfreq *devfreq;

•   struct opp_table        *opp_table;
  
    struct reset_control    *reset;
    struct clk              *clock;
  

@@ -612,34 +615,19 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra) static int tegra_devfreq_target(struct device *dev, unsigned long *freq, u32 flags) {

•   struct tegra_devfreq *tegra = dev_get_drvdata(dev);
  

•   struct devfreq *devfreq = tegra->devfreq;
    struct dev_pm_opp *opp;
  

•   unsigned long rate;
  

•   int err;
  

•   int ret;
  
    opp = devfreq_recommended_opp(dev, freq, flags);
    if (IS_ERR(opp)) {
  

•           dev_err(dev, "Failed to find opp for %lu Hz\n", *freq);
  

•           dev_err(dev, "failed to find opp for %lu Hz\n", *freq);
            return PTR_ERR(opp);
    }
  

•   rate = dev_pm_opp_get_freq(opp);
  

•   dev_pm_opp_put(opp);
  

•   err = clk_set_min_rate(tegra->emc_clock, rate * KHZ);
  

•   if (err)
  

•           return err;
  

•   err = clk_set_rate(tegra->emc_clock, 0);
  

•   if (err)
  

•           goto restore_min_rate;
  
  

•   return 0;
  

-restore_min_rate:

•   clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq);
  

•   ret = dev_pm_opp_set_bw(dev, opp);
  

•   dev_pm_opp_put(opp);
  
  

•   return err;
  

•   return ret;
  

}

static int tegra_devfreq_get_dev_status(struct device *dev, @@ -655,7 +643,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev, stat->private_data = tegra;

    /* The below are to be used by the other governors */

•   stat->current_frequency = cur_freq;
  

•   stat->current_frequency = cur_freq * KHZ;
  

I can't find any change related to the frequency unit on this patch. Do you fix the previous bug of the frequency unit?

    actmon_dev = &tegra->devices[MCALL];

@@ -705,7 +693,7 @@ static int tegra_governor_get_target(struct devfreq *devfreq, target_freq = max(target_freq, dev->target_freq); }

•   *freq = target_freq;
  

•   *freq = target_freq * KHZ;
  

ditto.

    return 0;

} @@ -773,13 +761,22 @@ static struct devfreq_governor tegra_devfreq_governor = {

static int tegra_devfreq_probe(struct platform_device *pdev) {

•   u32 hw_version = BIT(tegra_sku_info.soc_speedo_id);
    struct tegra_devfreq_device *dev;
    struct tegra_devfreq *tegra;
  

•   struct opp_table *opp_table;
    struct devfreq *devfreq;
    unsigned int i;
    long rate;
    int err;
  
  

•   /* legacy device-trees don't have OPP table and must be updated */
  

•   if (!device_property_present(&pdev->dev, "operating-points-v2")) {
  

•           dev_err(&pdev->dev, "OPP table not found, cannot continue\n");
  

•           dev_err(&pdev->dev, "please update your device tree\n");
  

•           return -ENODEV;
  

•   }
  

As you mentioned, it breaks the old dtb. I have no objection to improving the driver. Instead, you need confirmation from the Devicetree maintainer.

And, I recommend that you use dev_pm_opp_of_get_opp_desc_node(&pdev->dev) to check whether a device contains opp-table or not.

•   tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
    if (!tegra)
            return -ENOMEM;
  

@@ -821,11 +818,29 @@ static int tegra_devfreq_probe(struct platform_device *pdev) return err; }

•   tegra->opp_table = dev_pm_opp_get_opp_table(&pdev->dev);
  

•   if (IS_ERR(tegra->opp_table))
  

•           return dev_err_probe(&pdev->dev, PTR_ERR(tegra->opp_table),
  

•                                "Failed to prepare OPP table\n");
  

As I knew, each device can contain the opp_table on devicetree. It means that opp_table has not depended to another device driver. Did you see this exception case with EPROBE_DEFER error?

•   opp_table = dev_pm_opp_set_supported_hw(&pdev->dev, &hw_version, 1);
  

•   err = PTR_ERR_OR_ZERO(opp_table);
  

•   if (err) {
  

•           dev_err(&pdev->dev, "Failed to set supported HW: %d\n", err);
  

•           goto put_table;
  

•   }
  

•   err = dev_pm_opp_of_add_table(&pdev->dev);
  

•   if (err) {
  

•           dev_err(&pdev->dev, "Failed to add OPP table: %d\n", err);
  

•           goto put_hw;
  

•   }
  

•   err = clk_prepare_enable(tegra->clock);
    if (err) {
            dev_err(&pdev->dev,
                    "Failed to prepare and enable ACTMON clock\n");
  

•           return err;
  

•           goto remove_table;
    }
  
    err = reset_control_reset(tegra->reset);
  

@@ -849,23 +864,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev) dev->regs = tegra->regs + dev->config->offset; }

•   for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
  

•           rate = clk_round_rate(tegra->emc_clock, rate);
  

•           if (rate < 0) {
  

•                   dev_err(&pdev->dev,
  

•                           "Failed to round clock rate: %ld\n", rate);
  

•                   err = rate;
  

•                   goto remove_opps;
  

•           }
  

•           err = dev_pm_opp_add(&pdev->dev, rate / KHZ, 0);
  

•           if (err) {
  

•                   dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
  

•                   goto remove_opps;
  

•           }
  

•   }
  

•   platform_set_drvdata(pdev, tegra);
  
    tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
  

@@ -881,7 +879,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev) }

    tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);

•   tegra_devfreq_profile.initial_freq /= KHZ;
  
    devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile,
                                 "tegra_actmon", NULL);
  

@@ -901,6 +898,12 @@ static int tegra_devfreq_probe(struct platform_device *pdev) reset_control_reset(tegra->reset); disable_clk: clk_disable_unprepare(tegra->clock); +remove_table:

•   dev_pm_opp_of_remove_table(&pdev->dev);
  

+put_hw:

•   dev_pm_opp_put_supported_hw(tegra->opp_table);
  

+put_table:

•   dev_pm_opp_put_opp_table(tegra->opp_table);
  
    return err;
  

} @@ -912,11 +915,13 @@ static int tegra_devfreq_remove(struct platform_device *pdev) devfreq_remove_device(tegra->devfreq); devfreq_remove_governor(&tegra_devfreq_governor);

•   dev_pm_opp_remove_all_dynamic(&pdev->dev);
  

•   reset_control_reset(tegra->reset);
    clk_disable_unprepare(tegra->clock);
  
  

•   dev_pm_opp_of_remove_table(&pdev->dev);
  

•   dev_pm_opp_put_supported_hw(tegra->opp_table);
  

•   dev_pm_opp_put_opp_table(tegra->opp_table);
  

•   return 0;
  

}

-- 2.27.0