On Tue, Sep 22, 2026 at 09:45:03PM +0100, Karunika Choo wrote:
> On Mali v15 AM systems, frequency scaling is handled outside panthor by
> the AM_GOVERNOR block, so the GPU DT node may not provide an OPP table.
>
> Make panthor_devfreq_init() return early when dev_pm_opp_get_opp_table()
> returns -ENODEV, and guard the devfreq helper paths against a missing
> devfreq instance. Also make it so that frequency can be queried even if
> the devfreq instance is missing.
>
> This keeps devfreq enabled for existing platforms while allowing v15 AM
> systems to probe without a local devfreq setup.
>
> Signed-off-by: Karunika Choo <[email protected]>
> ---
> v1:
> - Only skip panthor_devfreq init when OPP lookup returns -ENODEV instead
> of direct DT-property check.
> - Support frequency query without devfreq.
>
> drivers/gpu/drm/panthor/panthor_devfreq.c | 31 ++++++++++++++++++-----
> drivers/gpu/drm/panthor/panthor_hw.h | 6 +++++
> 2 files changed, 30 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.c
> b/drivers/gpu/drm/panthor/panthor_devfreq.c
> index 2249b41ca4afe..18c1a7e56ca08 100644
> --- a/drivers/gpu/drm/panthor/panthor_devfreq.c
> +++ b/drivers/gpu/drm/panthor/panthor_devfreq.c
> @@ -12,6 +12,7 @@
>
> #include "panthor_devfreq.h"
> #include "panthor_device.h"
> +#include "panthor_hw.h"
>
> /**
> * struct panthor_devfreq - Device frequency management
> @@ -164,6 +165,19 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
> */
> table = dev_pm_opp_get_opp_table(dev);
> if (IS_ERR_OR_NULL(table)) {
> + /*
> + * On v15 GPUs, frequency scaling is handled outside of panthor
> + * by the AM_GOVERNOR block, so the GPU DT node may not provide
> + * an OPP table. In such cases, do not initialize devfreq for
> + * panthor.
> + */
> + if (panthor_hw_is_gen5_am(ptdev->base.dev) &&
> + PTR_ERR(table) == -ENODEV) {
> + drmm_kfree(&ptdev->base, pdevfreq);
> + ptdev->devfreq = NULL;
> + return 0;
> + }
> +
> ret = devm_pm_opp_set_regulators(dev, reg_names);
> if (ret && ret != -ENODEV) {
> if (ret != -EPROBE_DEFER)
> @@ -267,7 +281,7 @@ void panthor_devfreq_resume(struct panthor_device *ptdev)
> {
> struct panthor_devfreq *pdevfreq = ptdev->devfreq;
>
> - if (!pdevfreq->devfreq)
> + if (!pdevfreq || !pdevfreq->devfreq)
> return;
>
> panthor_devfreq_reset(pdevfreq);
> @@ -279,7 +293,7 @@ void panthor_devfreq_suspend(struct panthor_device *ptdev)
> {
> struct panthor_devfreq *pdevfreq = ptdev->devfreq;
>
> - if (!pdevfreq->devfreq)
> + if (!pdevfreq || !pdevfreq->devfreq)
> return;
>
> drm_WARN_ON(&ptdev->base, devfreq_suspend_device(pdevfreq->devfreq));
> @@ -290,7 +304,7 @@ void panthor_devfreq_record_busy(struct panthor_device
> *ptdev)
> struct panthor_devfreq *pdevfreq = ptdev->devfreq;
> unsigned long irqflags;
>
> - if (!pdevfreq->devfreq)
> + if (!pdevfreq || !pdevfreq->devfreq)
> return;
>
> spin_lock_irqsave(&pdevfreq->lock, irqflags);
> @@ -306,7 +320,7 @@ void panthor_devfreq_record_idle(struct panthor_device
> *ptdev)
> struct panthor_devfreq *pdevfreq = ptdev->devfreq;
> unsigned long irqflags;
>
> - if (!pdevfreq->devfreq)
> + if (!pdevfreq || !pdevfreq->devfreq)
> return;
>
> spin_lock_irqsave(&pdevfreq->lock, irqflags);
> @@ -319,14 +333,17 @@ void panthor_devfreq_record_idle(struct panthor_device
> *ptdev)
>
> unsigned long panthor_devfreq_get_freq(struct panthor_device *ptdev)
> {
> + int (*get_cur_freq)(struct device *dev, unsigned long *freq);
> struct panthor_devfreq *pdevfreq = ptdev->devfreq;
> unsigned long freq = 0;
> int ret;
>
> - if (!pdevfreq->devfreq)
> - return 0;
> + if (!pdevfreq || !pdevfreq->devfreq)
> + get_cur_freq = panthor_devfreq_get_cur_freq;
> + else
> + get_cur_freq = pdevfreq->devfreq->profile->get_cur_freq;
You don't need the whole pointer to a function dance. You can just do:
--8<-------------------------------------------
+ if (!pdevfreq || !pdevfreq->devfreq)
+ ret = panthor_devfreq_get_cur_freq(ptdev->base.dev, &freq);
+ else
+ ret = pdevfreq->devfreq->profile->get_cur_freq(ptdev->base.dev,
&freq);
if (ret)
return 0;
-->8-------------------------------------------
With that,
Reviewed-by: Liviu Dudau <[email protected]>
Best regards,
Liviu
>
> - ret = pdevfreq->devfreq->profile->get_cur_freq(ptdev->base.dev, &freq);
> + ret = get_cur_freq(ptdev->base.dev, &freq);
> diff --git a/drivers/gpu/drm/panthor/panthor_hw.h
> b/drivers/gpu/drm/panthor/panthor_hw.h
> index 48232254fef97..e5bcb908068cb 100644
> --- a/drivers/gpu/drm/panthor/panthor_hw.h
> +++ b/drivers/gpu/drm/panthor/panthor_hw.h
> @@ -101,4 +101,10 @@ static inline u64 panthor_hw_get_l2_features(struct
> panthor_device *ptdev)
> return ptdev->gpu_info.l2_features;
> }
>
> +static inline bool panthor_hw_is_gen5_am(struct device *dev)
> +{
> + return device_property_match_string(dev, "compatible",
> + "arm,mali-gen5-am") >= 0;
> +}
> +
> #endif /* __PANTHOR_HW_H__ */
> --
> 2.43.0
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
