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Message-ID: <nfftvqqdqqe7kmogvrf3ptmfj7bsnafeef57favlb3ck2pqany@rj64ut3glgor>
Date: Mon, 11 Aug 2025 18:07:46 +0100
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Lukas Zapolskas <lukas.zapolskas@....com>
Cc: dri-devel@...ts.freedesktop.org, nd@....com,
Boris Brezillon <boris.brezillon@...labora.com>, Steven Price <steven.price@....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>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 6/7] drm/panthor: Add suspend, resume and reset
handling
On 25.07.2025 15:57, Lukas Zapolskas wrote:
> The sampler must disable and re-enable counter sampling around
> suspends, and must re-program the FW interface after a reset to
> avoid losing data.
>
> Signed-off-by: Lukas Zapolskas <lukas.zapolskas@....com>
Reviewed-by: Adrián Larumbe <adrian.larumbe@...labora.com>
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 7 +-
> drivers/gpu/drm/panthor/panthor_perf.c | 89 ++++++++++++++++++++++++
> drivers/gpu/drm/panthor/panthor_perf.h | 6 ++
> 3 files changed, 101 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index ab3e65cc17bd..4bcf257e1403 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -139,6 +139,7 @@ static void panthor_device_reset_work(struct work_struct *work)
> if (!drm_dev_enter(&ptdev->base, &cookie))
> return;
>
> + panthor_perf_pre_reset(ptdev);
> panthor_sched_pre_reset(ptdev);
> panthor_fw_pre_reset(ptdev, true);
> panthor_mmu_pre_reset(ptdev);
> @@ -148,6 +149,7 @@ static void panthor_device_reset_work(struct work_struct *work)
> ret = panthor_fw_post_reset(ptdev);
> atomic_set(&ptdev->reset.pending, 0);
> panthor_sched_post_reset(ptdev, ret != 0);
> + panthor_perf_post_reset(ptdev);
> drm_dev_exit(cookie);
>
> if (ret) {
> @@ -503,8 +505,10 @@ int panthor_device_resume(struct device *dev)
> ret = panthor_device_resume_hw_components(ptdev);
> }
>
> - if (!ret)
> + if (!ret) {
> panthor_sched_resume(ptdev);
> + panthor_perf_resume(ptdev);
> + }
>
> drm_dev_exit(cookie);
>
> @@ -568,6 +572,7 @@ int panthor_device_suspend(struct device *dev)
> /* We prepare everything as if we were resetting the GPU.
> * The end of the reset will happen in the resume path though.
> */
> + panthor_perf_suspend(ptdev);
> panthor_sched_suspend(ptdev);
> panthor_fw_suspend(ptdev);
> panthor_mmu_suspend(ptdev);
> diff --git a/drivers/gpu/drm/panthor/panthor_perf.c b/drivers/gpu/drm/panthor/panthor_perf.c
> index fd16039d9244..512bbdb0aac1 100644
> --- a/drivers/gpu/drm/panthor/panthor_perf.c
> +++ b/drivers/gpu/drm/panthor/panthor_perf.c
> @@ -1845,6 +1845,63 @@ void panthor_perf_session_destroy(struct panthor_file *pfile, struct panthor_per
> }
> }
>
> +/**
> + * panthor_perf_suspend - Prepare the performance counter subsystem for system suspend.
> + * @ptdev: Panthor device.
> + *
> + * Indicate to the performance counters that the system is suspending.
> + *
> + * This function must not be used to handle MCU power state transitions: just before MCU goes
> + * from on to any inactive state, an automatic sample will be performed by the firmware, and
> + * the performance counter firmware state will be restored on warm boot.
> + *
> + */
> +void panthor_perf_suspend(struct panthor_device *ptdev)
> +{
> + int ret;
> + struct panthor_perf *perf = ptdev->perf;
> + struct panthor_perf_sampler *sampler;
> +
> + if (!perf)
> + return;
> +
> + sampler = &perf->sampler;
> +
> + if (!atomic_read(&sampler->enabled_clients))
> + return;
> +
> + ret = panthor_perf_fw_stop_sampling(sampler->ptdev);
> + if (ret)
> + drm_warn(&ptdev->base, "Could not stop sampling before suspend, err = %d", ret);
> +}
> +
> +/**
> + * panthor_perf_resume - Resume the performance counter subsystem after system resumption.
> + * @ptdev: Panthor device.
> + *
> + * Indicate to the performance counters that the system has resumed. This must not be used
> + * to handle MCU state transitions, for the same reasons as detailed in the kerneldoc for
> + * @panthor_perf_suspend.
> + */
> +void panthor_perf_resume(struct panthor_device *ptdev)
> +{
> + int ret;
> + struct panthor_perf *perf = ptdev->perf;
> + struct panthor_perf_sampler *sampler;
> +
> + if (!perf)
> + return;
> +
> + sampler = &perf->sampler;
> +
> + if (!atomic_read(&sampler->enabled_clients))
> + return;
> +
> + ret = panthor_perf_fw_start_sampling(sampler->ptdev);
> + if (ret)
> + drm_warn(&ptdev->base, "Could not resume sampling, err = %d", ret);
> +}
> +
> /**
> * panthor_perf_unplug - Terminate the performance counter subsystem.
> * @ptdev: Panthor device.
> @@ -1878,3 +1935,35 @@ void panthor_perf_unplug(struct panthor_device *ptdev)
>
> ptdev->perf = NULL;
> }
> +
> +void panthor_perf_pre_reset(struct panthor_device *ptdev)
> +{
> + struct panthor_perf_sampler *sampler;
> +
> + if (drm_WARN_ON_ONCE(&ptdev->base, !ptdev->perf))
> + return;
> +
> + sampler = &ptdev->perf->sampler;
> +
> + if (!atomic_read(&sampler->enabled_clients))
> + return;
> +
> + panthor_perf_fw_stop_sampling(sampler->ptdev);
> +}
> +
> +void panthor_perf_post_reset(struct panthor_device *ptdev)
> +{
> + struct panthor_perf_sampler *sampler;
> +
> + if (drm_WARN_ON_ONCE(&ptdev->base, !ptdev->perf))
> + return;
> +
> + sampler = &ptdev->perf->sampler;
> +
> + if (!atomic_read(&sampler->enabled_clients))
> + return;
> +
> + panthor_perf_fw_write_sampler_config(sampler);
> +
> + panthor_perf_fw_start_sampling(sampler->ptdev);
> +}
> diff --git a/drivers/gpu/drm/panthor/panthor_perf.h b/drivers/gpu/drm/panthor/panthor_perf.h
> index 5a14854368eb..1044b0a1cfaa 100644
> --- a/drivers/gpu/drm/panthor/panthor_perf.h
> +++ b/drivers/gpu/drm/panthor/panthor_perf.h
> @@ -14,6 +14,8 @@ struct panthor_file;
> struct panthor_perf;
>
> int panthor_perf_init(struct panthor_device *ptdev);
> +void panthor_perf_suspend(struct panthor_device *ptdev);
> +void panthor_perf_resume(struct panthor_device *ptdev);
> void panthor_perf_unplug(struct panthor_device *ptdev);
>
> int panthor_perf_session_setup(struct drm_file *file, struct panthor_perf *perf,
> @@ -30,5 +32,9 @@ void panthor_perf_session_destroy(struct panthor_file *pfile, struct panthor_per
>
> void panthor_perf_report_irq(struct panthor_device *ptdev, u32 status);
>
> +void panthor_perf_pre_reset(struct panthor_device *ptdev);
> +
> +void panthor_perf_post_reset(struct panthor_device *ptdev);
> +
> #endif /* __PANTHOR_PERF_H__ */
>
> --
> 2.33.0.dirty
Adrian Larumbe
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