On Fri, 16 Jan 2026 13:57:29 +0100 Nicolas Frattaroli <[email protected]> wrote:
> This series adds two tracepoints to panthor. > > The first tracepoint allows for inspecting the power status of the > hardware subdivisions, e.g. how many shader cores are powered on. This > is done by reading three hardware registers when a certain IRQ fires. > > The second tracepoint instruments panthor's job IRQ handler. This is > more useful than the generic interrupt tracing functionality, as the > tracepoint has the events bit mask included, which indicates which > command stream group interfaces triggered the interrupt. > > To test the tracepoints, the following can be used: > > :~# echo 1 > /sys/kernel/tracing/events/panthor/gpu_power_status/enable > :~# echo 1 > /sys/kernel/tracing/events/panthor/gpu_job_irq/enable > :~# echo 1 > /sys/kernel/tracing/tracing_on > :~# cat /sys/kernel/tracing/trace_pipe > > Signed-off-by: Nicolas Frattaroli <[email protected]> Queued to drm-misc-next. > --- > Changes in v10: > - Start processing phase in raw_irq_handler (Boris) > - enable/disable_events: Only write mask contents in ACTIVE state > (Boris) > - Elaborate on what mask_lock protects in comment (Boris) > - nb: checkpatch reports unnecessary line continuations in the macros > at the end of the comment blocks. These warnings are false-positives, > the line continuations are necessary. > - Link to v9: > https://lore.kernel.org/r/[email protected] > > Changes in v9: > - Rebase onto drm-tip 2026y-01m-14d-17h-09m-04s > - Move the mask to pirq->mask change in the suspended refactor patch to > the follow-up patch > - Move the INT_MASK restoration changes in the suspended refactor patch > to the follow-up patch > - Move panthor_irq::mask_lock member right below the mask member > - panthor/mmu: Remove the enable_events calls before resume, as they're > redundant > - panthor/mmu: Rework the AS fault clearing logic. Drop the spurious > disable_events in panthor_vm_active, but use > disable_events/enable_events in as_disable/as_enable respectively. This > requires doing a forward declaration of the panthor_mmu_irq_handler to > get a definition of the helpers before it itself is defined. This > works out great, because it means I also no longer have to move the > entire panthor_vm_active function down some. > - Drop an accidentally added redundant empty line > - Link to v8: > https://lore.kernel.org/r/[email protected] > > Changes in v8: > - Reorder panthor_irq::state patch to be before the new mask > modification helpers. The full set of states was kept (rather than > just active/suspended) as they don't hurt and make the follow-up patch > more concise in scope. > - Also bail out on STATE_SUSPENDING in irq_raw_handler > - Job irq: initialize start to 0 and don't emit a tracepoint if it is 0, > to fix passing an uninitialised stack variable to userspace if the > tracepoint was enabled while the handler was running > - Link to v7: > https://lore.kernel.org/r/[email protected] > > Changes in v7: > - Get rid of old resume IRQ helper by reworking code throughout panthor, > and make what used to be resume_restore in v6 the new resume. > - Rename mask_enable/mask_disable to enable_events/disable_events. > - Turn panthor_irq::suspended into a multi-state value, and utilise it > in the IRQ helpers as appropriate. > - Link to v6: > https://lore.kernel.org/r/[email protected] > > Changes in v6: > - Read the mask member into a local while holding the lock in > irq_threaded_handler. > - Drop the lock before entering the while loop, letting the threaded > handler function run without holding a spinlock > - Re-acquire the spinlock at the end of irq_threaded_handler, OR'ing the > mask register's contents with the mask local ANDed by the member. This > avoids stomping over any other modified bits, or restoring ones that > have been disabled in the meantime. > - Link to v5: > https://lore.kernel.org/r/[email protected] > > Changes in v5: > - Change the panthor IRQ helpers to guard the mask member and register > with a spinlock. The rationale behind using a spinlock, rather than > some constellation of atomics, is that we have to guarantee mutual > exclusion for state beyond just a single value, namely both the register > write, and writes to/reads from the mask member, including > reads-from-member-writes-to-register. Making the mask atomic does not do > anything to avoid concurrency issues in such a case. > - Change the IRQ mask member to not get zeroed when suspended. It's > possible something outside of the IRQ helpers depends on this > behaviour, but I'd argue the code should not access the mask outside > of the IRQ helpers, as it'll do so with no lock taken. > - Drop the mask_set function, but add mask_enable/mask_disable helpers > to enable/disable individual parts of the IRQ mask. > - Add a resume_restore IRQ helper that does the same thing as resume, > but does not overwrite the mask member. This avoids me having to > refactor whatever panthor_mmu.c is doing with that poor mask member. > - Link to v4: > https://lore.kernel.org/r/[email protected] > > Changes in v4: > - Include "panthor_hw.h" in panthor_trace.h instead of duplicating the > reg/unreg function prototypes. > - Link to v3: > https://lore.kernel.org/r/[email protected] > > Changes in v3: > - Drop PWRFEATURES patch, as this register is no longer needed by this > series. > - Eliminate the rt_on field from the gpu_power_status register, as per > Steven Price's feedback. > - Make gpu_power_status tracepoint reg/unreg functions generic across > hardware generations by wrapping a hw op in panthor_hw.c. > - Reimplement the <= v13 IRQ mask modification functions as the new hw > ops functions. v14 can add its own ops in due time. > - Link to v2: > https://lore.kernel.org/r/[email protected] > > Changes in v2: > - Only enable the GPU_IRQ_POWER_CHANGED_* IRQ mask bits when the > tracepoint is enabled. Necessitates the new irq helper patch. > - Only enable the GPU_IRQ_POWER_CHANGED_* IRQ mask bits if the hardware > architecture is <= v13, as v14 changes things. > - Use _READY instead of _PWRACTIVE registers, and rename the tracepoint > accordingly. > - Also read the status of the ray tracing unit's power. This is a global > flag for all shader cores, it seems. Necessitates the new register > definition patch. > - Move the POWER_CHANGED_* check to earlier in the interrupt handler. > - Also listen to POWER_CHANGED, not just POWER_CHANGED_ALL, as this > provides useful information with the _READY registers. > - Print the device name in both tracepoints, to disambiguate things on > systems with multiple Mali GPUs. > - Document the gpu_power_status tracepoint, so the meaning of the fields > is made clear. > - Link to v1: > https://lore.kernel.org/r/[email protected] > > --- > Nicolas Frattaroli (4): > drm/panthor: Rework panthor_irq::suspended into panthor_irq::state > drm/panthor: Extend IRQ helpers for mask modification/restoration > drm/panthor: Add tracepoint for hardware utilisation changes > drm/panthor: Add gpu_job_irq tracepoint > > drivers/gpu/drm/panthor/panthor_device.h | 107 > ++++++++++++++++++++++++++----- > drivers/gpu/drm/panthor/panthor_fw.c | 16 ++++- > drivers/gpu/drm/panthor/panthor_gpu.c | 30 ++++++++- > drivers/gpu/drm/panthor/panthor_gpu.h | 2 + > drivers/gpu/drm/panthor/panthor_hw.c | 62 ++++++++++++++++++ > drivers/gpu/drm/panthor/panthor_hw.h | 8 +++ > drivers/gpu/drm/panthor/panthor_mmu.c | 47 +++++++------- > drivers/gpu/drm/panthor/panthor_pwr.c | 2 +- > drivers/gpu/drm/panthor/panthor_trace.h | 86 +++++++++++++++++++++++++ > 9 files changed, 318 insertions(+), 42 deletions(-) > --- > base-commit: 733664f1edf3c01cc68e6dd0bbdb135158a98a1d > change-id: 20251203-panthor-tracepoints-488af09d46e7 > > Best regards,
