On 16/01/2026 12:57, Nicolas Frattaroli wrote: > Mali's CSF firmware triggers the job IRQ whenever there's new firmware > events for processing. While this can be a global event (BIT(31) of the > status register), it's usually an event relating to a command stream > group (the other bit indices). > > Panthor throws these events onto a workqueue for processing outside the > IRQ handler. It's therefore useful to have an instrumented tracepoint > that goes beyond the generic IRQ tracepoint for this specific case, as > it can be augmented with additional data, namely the events bit mask. > > This can then be used to debug problems relating to GPU jobs events not > being processed quickly enough. The duration_ns field can be used to > work backwards from when the tracepoint fires (at the end of the IRQ > handler) to figure out when the interrupt itself landed, providing not > just information on how long the work queueing took, but also when the > actual interrupt itself arrived. > > With this information in hand, the IRQ handler itself being slow can be > excluded as a possible source of problems, and attention can be directed > to the workqueue processing instead. > > Signed-off-by: Nicolas Frattaroli <[email protected]>
Reviewed-by: Steven Price <[email protected]> > --- > drivers/gpu/drm/panthor/panthor_fw.c | 13 +++++++++++++ > drivers/gpu/drm/panthor/panthor_trace.h | 28 ++++++++++++++++++++++++++++ > 2 files changed, 41 insertions(+) > > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c > b/drivers/gpu/drm/panthor/panthor_fw.c > index 0e46625f7621..5a904ca64525 100644 > --- a/drivers/gpu/drm/panthor/panthor_fw.c > +++ b/drivers/gpu/drm/panthor/panthor_fw.c > @@ -26,6 +26,7 @@ > #include "panthor_mmu.h" > #include "panthor_regs.h" > #include "panthor_sched.h" > +#include "panthor_trace.h" > > #define CSF_FW_NAME "mali_csffw.bin" > > @@ -1060,6 +1061,12 @@ static void panthor_fw_init_global_iface(struct > panthor_device *ptdev) > > static void panthor_job_irq_handler(struct panthor_device *ptdev, u32 status) > { > + u32 duration; > + u64 start = 0; > + > + if (tracepoint_enabled(gpu_job_irq)) > + start = ktime_get_ns(); > + > gpu_write(ptdev, JOB_INT_CLEAR, status); > > if (!ptdev->fw->booted && (status & JOB_INT_GLOBAL_IF)) > @@ -1072,6 +1079,12 @@ static void panthor_job_irq_handler(struct > panthor_device *ptdev, u32 status) > return; > > panthor_sched_report_fw_events(ptdev, status); > + > + if (tracepoint_enabled(gpu_job_irq) && start) { > + if (check_sub_overflow(ktime_get_ns(), start, &duration)) > + duration = U32_MAX; > + trace_gpu_job_irq(ptdev->base.dev, status, duration); > + } > } > PANTHOR_IRQ_HANDLER(job, JOB, panthor_job_irq_handler); > > diff --git a/drivers/gpu/drm/panthor/panthor_trace.h > b/drivers/gpu/drm/panthor/panthor_trace.h > index 5bd420894745..6ffeb4fe6599 100644 > --- a/drivers/gpu/drm/panthor/panthor_trace.h > +++ b/drivers/gpu/drm/panthor/panthor_trace.h > @@ -48,6 +48,34 @@ TRACE_EVENT_FN(gpu_power_status, > panthor_hw_power_status_register, panthor_hw_power_status_unregister > ); > > +/** > + * gpu_job_irq - called after a job interrupt from firmware completes > + * @dev: pointer to the &struct device, for printing the device name > + * @events: bitmask of BIT(CSG id) | BIT(31) for a global event > + * @duration_ns: Nanoseconds between job IRQ handler entry and exit > + * > + * The panthor_job_irq_handler() function instrumented by this tracepoint > exits > + * once it has queued the firmware interrupts for processing, not when the > + * firmware interrupts are fully processed. This tracepoint allows for > debugging > + * issues with delays in the workqueue's processing of events. > + */ > +TRACE_EVENT(gpu_job_irq, > + TP_PROTO(const struct device *dev, u32 events, u32 duration_ns), > + TP_ARGS(dev, events, duration_ns), > + TP_STRUCT__entry( > + __string(dev_name, dev_name(dev)) > + __field(u32, events) > + __field(u32, duration_ns) > + ), > + TP_fast_assign( > + __assign_str(dev_name); > + __entry->events = events; > + __entry->duration_ns = duration_ns; > + ), > + TP_printk("%s: events=0x%x duration_ns=%d", __get_str(dev_name), > + __entry->events, __entry->duration_ns) > +); > + > #endif /* __PANTHOR_TRACE_H__ */ > > #undef TRACE_INCLUDE_PATH >
