[PATCH RFC 06/10] drm/panthor: call into devfreq for current frequency

[Steven Price]

On 05/09/2025 11:23, 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.
> 
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli at collabora.com>

Reviewed-by: Steven Price <steven.price at arm.com>

> ---
>  drivers/gpu/drm/panthor/panthor_devfreq.c | 33 +++++++++++++++++++++++++++----
>  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, 34 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.c b/drivers/gpu/drm/panthor/panthor_devfreq.c
> index 3686515d368db5bb329f4858d4a7247a4957cc24..8903f60c0a3f06313ac2008791c210ff32b6bd52 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)
> @@ -198,7 +205,6 @@ 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
> @@ -296,3 +302,22 @@ 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 || !pdevfreq->devfreq)
> +		return 0;
> +
> +	if (pdevfreq->devfreq->profile->get_cur_freq) {
> +		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 b7631de695f7d79456478c87e8af5dc47673cd1d..f8e29e02f66cb3281ed4bb4c75cda9bd4df82b92 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 4fc7cf2aeed577f623aac73ed287d6327645ecaa..a14239c8f9ca9229d8d6d36d327e6fd6d05f8f2f 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -200,9 +200,6 @@ 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 4c202fc5ce0504e3f08bf6c8f18a314890eb88ec..c85a16e1339eaa164a8719ffecf5214cafff1a55 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)
>