Re: [PATCH 2/2] drm/panfrost: add devfreq regulator support

Hi Steven,

On Mon, 13 Apr 2020 at 15:18, Steven Price steven.price@arm.com wrote:

On 11/04/2020 21:06, Clément Péron wrote:

...

OPP table can defined both frequency and voltage.

Register the mali regulator if it exist.

Signed-off-by: Clément Péron peron.clem@gmail.com

drivers/gpu/drm/panfrost/panfrost_devfreq.c | 34 ++++++++++++++++++--- drivers/gpu/drm/panfrost/panfrost_device.h | 1 + 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c index 62541f4edd81..2dc8e2355358 100644 --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c @@ -78,12 +78,26 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev) struct device *dev = &pfdev->pdev->dev; struct devfreq *devfreq; struct thermal_cooling_device *cooling;

• const char *mali = "mali";
  

• struct opp_table *opp_table = NULL;
  

• /* Regulator is optional */
  

• opp_table = dev_pm_opp_set_regulators(dev, &mali, 1);
  

This looks like it applies before 3e1399bccf51 ("drm/panfrost: Add support for multiple regulators") which is currently in drm-misc-next (and linux-next). You want something more like:

Thanks for you review, indeed I didn't see that multiple regulators support has been added. Will update in v2.

 opp_table = dev_pm_opp_set_regulators(dev,
                                       pfdev->comp->supply_names,
                                       pfdev->comp->num_supplies);

Otherwise a platform with multiple regulators won't work correctly.

Also running on my firefly (RK3288) board I get the following warning:

debugfs: Directory 'ffa30000.gpu-mali' with parent 'vdd_gpu' already

present!

This is due to the regulator debugfs entries getting created twice (once in panfrost_regulator_init() and once here).

Is it a warning that should be consider as an error? Look's more an info no? What should be the correct behavior if a device want to register two times the same regulator?

Link to original discussion: https://lore.kernel.org/patchwork/patch/1176717/

Thanks, Clement

I have been taking a look at doing the same thing (I picked up Martin Blumenstingl's patch series[1]), but haven't had much time to focus on this recently.

Thanks,

Steve

[1] https://lore.kernel.org/dri-devel/20200112001623.2121227-1-martin.blumenstin...

...

• if (IS_ERR(opp_table)) {
  

•         ret = PTR_ERR(opp_table);
  

•         if (ret != -ENODEV) {
  

•                 DRM_DEV_ERROR(dev, "Failed to set regulator: %d\n", ret);
  

•                 return ret;
  

•         }
  

• }
  

• pfdev->devfreq.opp_table = opp_table;
  
  ret = dev_pm_opp_of_add_table(dev);
  

• if (ret == -ENODEV) /* Optional, continue without devfreq */
  

•         return 0;
  

• else if (ret)
  

•         return ret;
  

• if (ret) {
  

•         if (ret == -ENODEV) /* Optional, continue without devfreq */
  

•                 ret = 0;
  

•         goto err_opp_reg;
  

• }
  
  panfrost_devfreq_reset(pfdev);
  
  

@@ -119,6 +133,12 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev) err_opp: dev_pm_opp_of_remove_table(dev);

+err_opp_reg:

• if (pfdev->devfreq.opp_table) {
  

•         dev_pm_opp_put_regulators(pfdev->devfreq.opp_table);
  

•         pfdev->devfreq.opp_table = NULL;
  

• }
  

• return ret;
  

  }

@@ -126,7 +146,13 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev) { if (pfdev->devfreq.cooling) devfreq_cooling_unregister(pfdev->devfreq.cooling);

• dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
  

• if (pfdev->devfreq.opp_table) {
  

•         dev_pm_opp_put_regulators(pfdev->devfreq.opp_table);
  

•         pfdev->devfreq.opp_table = NULL;
  

• }
  

  }

  void panfrost_devfreq_resume(struct panfrost_device *pfdev)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h index 06713811b92c..f6b0c779dfe5 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.h +++ b/drivers/gpu/drm/panfrost/panfrost_device.h @@ -86,6 +86,7 @@ struct panfrost_device { struct { struct devfreq *devfreq; struct thermal_cooling_device *cooling;

•         struct opp_table *opp_table;
          ktime_t busy_time;
          ktime_t idle_time;
          ktime_t time_last_update;