On Wed, Dec 3, 2025 at 6:04 AM Nicolas Frattaroli <[email protected]> wrote: > > Mali GPUs have three registers that indicate which parts of the hardware > are powered and active at any moment. These take the form of bitmaps. In > the case of SHADER_PWRACTIVE for example, a high bit indicates that the > shader core corresponding to that bit index is active. These bitmaps > aren't solely contiguous bits, as it's common to have holes in the > sequence of shader core indices, and the actual set of which cores are > present is defined by the "shader present" register. > > When the GPU finishes a power state transition, it fires a > GPU_IRQ_POWER_CHANGED_ALL interrupt. After such an interrupt is > received, the PWRACTIVE registers will likely contain interesting new > information. I am seeing
irq/342-panthor-412 [000] ..... 934.526754: gpu_power_active: shader_bitmap=0x0 tiler_bitmap=0x0 l2_bitmap=0x0 irq/342-panthor-412 [000] ..... 936.640356: gpu_power_active: shader_bitmap=0x0 tiler_bitmap=0x0 l2_bitmap=0x0 on a gpu-bound test. It does not look like collecting samples on GPU_IRQ_POWER_CHANGED_ALL gives too much info. I think they are more useful to be collected periodically, such that we know that in the past X seconds, Y out of a total of Z samples indicates activities. That's best done in userspace, and panthor's role should be to provide an uapi such as https://lore.kernel.org/all/[email protected]/. > > This is not to be confused with the PWR_IRQ_POWER_CHANGED_ALL interrupt, > which is something related to Mali v14+'s power control logic. The > PWRACTIVE registers and corresponding interrupts are already available > in v9 and onwards. > > Expose this as a tracepoint to userspace. This allows users to debug > various scenarios and gather interesting information, such as: knowing > how much hardware is lit up at any given time, correlating graphics > corruption with a specific active shader core, measuring when hardware > is allowed to go to an inactive state again, and so on. > > Signed-off-by: Nicolas Frattaroli <[email protected]> > --- > drivers/gpu/drm/panthor/panthor_device.c | 1 + > drivers/gpu/drm/panthor/panthor_gpu.c | 9 ++++++++ > drivers/gpu/drm/panthor/panthor_trace.h | 38 > ++++++++++++++++++++++++++++++++ > 3 files changed, 48 insertions(+) > > diff --git a/drivers/gpu/drm/panthor/panthor_device.c > b/drivers/gpu/drm/panthor/panthor_device.c > index e133b1e0ad6d..a3cb934104b8 100644 > --- a/drivers/gpu/drm/panthor/panthor_device.c > +++ b/drivers/gpu/drm/panthor/panthor_device.c > @@ -548,6 +548,7 @@ int panthor_device_resume(struct device *dev) > DRM_PANTHOR_USER_MMIO_OFFSET, 0, 1); > atomic_set(&ptdev->pm.state, PANTHOR_DEVICE_PM_STATE_ACTIVE); > mutex_unlock(&ptdev->pm.mmio_lock); > + > return 0; > > err_suspend_devfreq: > diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c > b/drivers/gpu/drm/panthor/panthor_gpu.c > index 9cb5dee93212..8830aa9a5c4b 100644 > --- a/drivers/gpu/drm/panthor/panthor_gpu.c > +++ b/drivers/gpu/drm/panthor/panthor_gpu.c > @@ -22,6 +22,9 @@ > #include "panthor_hw.h" > #include "panthor_regs.h" > > +#define CREATE_TRACE_POINTS > +#include "panthor_trace.h" > + > /** > * struct panthor_gpu - GPU block management data. > */ > @@ -46,6 +49,7 @@ struct panthor_gpu { > (GPU_IRQ_FAULT | \ > GPU_IRQ_PROTM_FAULT | \ > GPU_IRQ_RESET_COMPLETED | \ > + GPU_IRQ_POWER_CHANGED_ALL | \ > GPU_IRQ_CLEAN_CACHES_COMPLETED) > > static void panthor_gpu_coherency_set(struct panthor_device *ptdev) > @@ -97,6 +101,11 @@ static void panthor_gpu_irq_handler(struct panthor_device > *ptdev, u32 status) > wake_up_all(&ptdev->gpu->reqs_acked); > } > spin_unlock(&ptdev->gpu->reqs_lock); > + > + if (status & GPU_IRQ_POWER_CHANGED_ALL) > + trace_gpu_power_active(gpu_read64(ptdev, SHADER_PWRACTIVE), > + gpu_read64(ptdev, TILER_PWRACTIVE), > + gpu_read64(ptdev, L2_PWRACTIVE)); > } > PANTHOR_IRQ_HANDLER(gpu, GPU, panthor_gpu_irq_handler); > > diff --git a/drivers/gpu/drm/panthor/panthor_trace.h > b/drivers/gpu/drm/panthor/panthor_trace.h > new file mode 100644 > index 000000000000..01013f81e68a > --- /dev/null > +++ b/drivers/gpu/drm/panthor/panthor_trace.h > @@ -0,0 +1,38 @@ > +/* SPDX-License-Identifier: GPL-2.0 or MIT */ > +/* Copyright 2025 Collabora ltd. */ > + > +#undef TRACE_SYSTEM > +#define TRACE_SYSTEM panthor > + > +#if !defined(__PANTHOR_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ) > +#define __PANTHOR_TRACE_H__ > + > +#include <linux/tracepoint.h> > +#include <linux/types.h> > + > +TRACE_EVENT(gpu_power_active, > + TP_PROTO(u64 shader_bitmap, u64 tiler_bitmap, u64 l2_bitmap), > + TP_ARGS(shader_bitmap, tiler_bitmap, l2_bitmap), > + TP_STRUCT__entry( > + __field(u64, shader_bitmap) > + __field(u64, tiler_bitmap) > + __field(u64, l2_bitmap) > + ), > + TP_fast_assign( > + __entry->shader_bitmap = shader_bitmap; > + __entry->tiler_bitmap = tiler_bitmap; > + __entry->l2_bitmap = l2_bitmap; > + ), > + TP_printk("shader_bitmap=0x%llx tiler_bitmap=0x%llx l2_bitmap=0x%llx", > + __entry->shader_bitmap, __entry->tiler_bitmap, > __entry->l2_bitmap > + ) > +); > + > +#endif /* __PANTHOR_TRACE_H__ */ > + > +#undef TRACE_INCLUDE_PATH > +#define TRACE_INCLUDE_PATH . > +#undef TRACE_INCLUDE_FILE > +#define TRACE_INCLUDE_FILE panthor_trace > + > +#include <trace/define_trace.h> > > -- > 2.52.0 >
