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Message-ID: <b4fd2074-d00f-4726-a85d-541105cdc6fd@arm.com>
Date: Wed, 10 Sep 2025 14:59:00 +0100
From: Steven Price <steven.price@....com>
To: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
Boris Brezillon <boris.brezillon@...labora.com>,
Liviu Dudau <liviu.dudau@....com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Matthias Brugger
<matthias.bgg@...il.com>, MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Chanwoo Choi <cw00.choi@...sung.com>, Jassi Brar <jassisinghbrar@...il.com>,
Kees Cook <kees@...nel.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Chia-I Wu <olvaffe@...il.com>, Chen-Yu Tsai <wenst@...omium.org>,
kernel@...labora.com, dri-devel@...ts.freedesktop.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
linux-pm@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH RFC 06/10] drm/panthor: call into devfreq for current
frequency
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@...labora.com>
Reviewed-by: Steven Price <steven.price@....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)
>
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