Re: [PATCH v8 3/5] drm/panthor: call into devfreq for current frequency

[Karunika Choo <karunika.choo@arm.com>]

On 17/10/2025 16:31, Nicolas Frattaroli wrote:
> As it stands, panthor keeps a cached current frequency value for when it
> wants to retrieve it. This doesn't work well for when things might
> switch frequency without panthor's knowledge.
> 
> Instead, implement the get_cur_freq operation, and expose it through a
> helper function to the rest of panthor.
> 
> Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
> Reviewed-by: Steven Price <steven.price@arm.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> ---
>  drivers/gpu/drm/panthor/panthor_devfreq.c | 30 ++++++++++++++++++++++++++----
>  drivers/gpu/drm/panthor/panthor_devfreq.h |  2 ++
>  drivers/gpu/drm/panthor/panthor_device.h  |  3 ---
>  drivers/gpu/drm/panthor/panthor_drv.c     |  4 +++-
>  4 files changed, 31 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.c b/drivers/gpu/drm/panthor/panthor_devfreq.c
> index 2df1d76d84a0..a6dca599f0a5 100644
> --- a/drivers/gpu/drm/panthor/panthor_devfreq.c
> +++ b/drivers/gpu/drm/panthor/panthor_devfreq.c
> @@ -62,7 +62,6 @@ static void panthor_devfreq_update_utilization(struct panthor_devfreq *pdevfreq)
>  static int panthor_devfreq_target(struct device *dev, unsigned long *freq,
>  				  u32 flags)
>  {
> -	struct panthor_device *ptdev = dev_get_drvdata(dev);
>  	struct dev_pm_opp *opp;
>  	int err;
>  
> @@ -72,8 +71,6 @@ static int panthor_devfreq_target(struct device *dev, unsigned long *freq,
>  	dev_pm_opp_put(opp);
>  
>  	err = dev_pm_opp_set_rate(dev, *freq);
> -	if (!err)
> -		ptdev->current_frequency = *freq;
>  
>  	return err;
>  }
> @@ -115,11 +112,21 @@ static int panthor_devfreq_get_dev_status(struct device *dev,
>  	return 0;
>  }
>  
> +static int panthor_devfreq_get_cur_freq(struct device *dev, unsigned long *freq)
> +{
> +	struct panthor_device *ptdev = dev_get_drvdata(dev);
> +
> +	*freq = clk_get_rate(ptdev->clks.core);
> +
> +	return 0;
> +}
> +
>  static struct devfreq_dev_profile panthor_devfreq_profile = {
>  	.timer = DEVFREQ_TIMER_DELAYED,
>  	.polling_ms = 50, /* ~3 frames */
>  	.target = panthor_devfreq_target,
>  	.get_dev_status = panthor_devfreq_get_dev_status,
> +	.get_cur_freq = panthor_devfreq_get_cur_freq,
>  };
>  
>  int panthor_devfreq_init(struct panthor_device *ptdev)
> @@ -197,7 +204,6 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
>  		return PTR_ERR(opp);
>  
>  	panthor_devfreq_profile.initial_freq = cur_freq;
> -	ptdev->current_frequency = cur_freq;
>  
>  	/*
>  	 * Set the recommend OPP this will enable and configure the regulator
> @@ -295,3 +301,19 @@ void panthor_devfreq_record_idle(struct panthor_device *ptdev)
>  
>  	spin_unlock_irqrestore(&pdevfreq->lock, irqflags);
>  }
> +
> +unsigned long panthor_devfreq_get_freq(struct panthor_device *ptdev)
> +{
> +	struct panthor_devfreq *pdevfreq = ptdev->devfreq;
> +	unsigned long freq = 0;
> +	int ret;
> +
> +	if (!pdevfreq->devfreq)
> +		return 0;
> +
> +	ret = pdevfreq->devfreq->profile->get_cur_freq(ptdev->base.dev, &freq);
> +	if (ret)
> +		return 0;
> +
> +	return freq;
> +}
> diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.h b/drivers/gpu/drm/panthor/panthor_devfreq.h
> index b7631de695f7..f8e29e02f66c 100644
> --- a/drivers/gpu/drm/panthor/panthor_devfreq.h
> +++ b/drivers/gpu/drm/panthor/panthor_devfreq.h
> @@ -18,4 +18,6 @@ void panthor_devfreq_suspend(struct panthor_device *ptdev);
>  void panthor_devfreq_record_busy(struct panthor_device *ptdev);
>  void panthor_devfreq_record_idle(struct panthor_device *ptdev);
>  
> +unsigned long panthor_devfreq_get_freq(struct panthor_device *ptdev);
> +
>  #endif /* __PANTHOR_DEVFREQ_H__ */
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index 9f0649ecfc4f..f32c1868bf6d 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -214,9 +214,6 @@ struct panthor_device {
>  	/** @profile_mask: User-set profiling flags for job accounting. */
>  	u32 profile_mask;
>  
> -	/** @current_frequency: Device clock frequency at present. Set by DVFS*/
> -	unsigned long current_frequency;
> -
>  	/** @fast_rate: Maximum device clock frequency. Set by DVFS */
>  	unsigned long fast_rate;
>  
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> index fb4b293f17f0..75898d83a207 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -25,6 +25,7 @@
>  #include <drm/gpu_scheduler.h>
>  #include <drm/panthor_drm.h>
>  
> +#include "panthor_devfreq.h"
>  #include "panthor_device.h"
>  #include "panthor_fw.h"
>  #include "panthor_gem.h"
> @@ -1519,7 +1520,8 @@ static void panthor_gpu_show_fdinfo(struct panthor_device *ptdev,
>  		drm_printf(p, "drm-cycles-panthor:\t%llu\n", pfile->stats.cycles);
>  
>  	drm_printf(p, "drm-maxfreq-panthor:\t%lu Hz\n", ptdev->fast_rate);
> -	drm_printf(p, "drm-curfreq-panthor:\t%lu Hz\n", ptdev->current_frequency);
> +	drm_printf(p, "drm-curfreq-panthor:\t%lu Hz\n",
> +		   panthor_devfreq_get_freq(ptdev));
>  }
>  
>  static void panthor_show_internal_memory_stats(struct drm_printer *p, struct drm_file *file)
> 

Reviewed-by: Karunika Choo <karunika.choo@arm.com>