On Wed, 12 Aug 2026 16:07:18 +0200 Nicolas Frattaroli <[email protected]> wrote:
> Add a new event tracepoint: gpu_cache_flush to be emitted after a GPU > cache flush completes, with duration and return status arguments. > > This allows debugging the duration a flush takes irrespective of initial > function entry lock contention, and communicates information about > whether the flush timed out or errored out in other ways, and which > caches were flushed. > > Signed-off-by: Nicolas Frattaroli <[email protected]> Reviewed-by: Boris Brezillon <[email protected]> > --- > drivers/gpu/drm/panthor/panthor_gpu.c | 26 +++++++++++++++++++++- > drivers/gpu/drm/panthor/panthor_trace.h | 38 > +++++++++++++++++++++++++++++++++ > 2 files changed, 63 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c > b/drivers/gpu/drm/panthor/panthor_gpu.c > index c013d6bf9a59..7088371c6d64 100644 > --- a/drivers/gpu/drm/panthor/panthor_gpu.c > +++ b/drivers/gpu/drm/panthor/panthor_gpu.c > @@ -317,6 +317,21 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev) > return panthor_gpu_power_on(ptdev, L2, 1, 20000); > } > > +static inline void panthor_gpu_emit_flush_caches_tp(struct panthor_device > *ptdev, > + u64 start, u32 l2, u32 lsc, > + u32 other, int ret) > +{ > + u32 duration; > + > + if (!tracepoint_enabled(gpu_cache_flush) || !start) > + return; > + > + if (check_sub_overflow(ktime_get_ns(), start, &duration)) > + duration = U32_MAX; > + > + trace_gpu_cache_flush(ptdev->base.dev, l2, lsc, other, duration, ret); > +} > + > /** > * panthor_gpu_flush_caches() - Flush caches > * @ptdev: Device. > @@ -331,12 +346,17 @@ int panthor_gpu_flush_caches(struct panthor_device > *ptdev, > { > struct panthor_gpu *gpu = ptdev->gpu; > unsigned long flags; > + u64 start = 0; > int ret = 0; > > /* Serialize cache flush operations. */ > guard(mutex)(&ptdev->gpu->cache_flush_lock); > > spin_lock_irqsave(&ptdev->gpu->reqs_lock, flags); > + > + if (tracepoint_enabled(gpu_cache_flush)) > + start = ktime_get_ns(); > + > if (!(ptdev->gpu->pending_reqs & GPU_IRQ_CLEAN_CACHES_COMPLETED)) { > ptdev->gpu->pending_reqs |= GPU_IRQ_CLEAN_CACHES_COMPLETED; > gpu_write(gpu->iomem, GPU_CMD, GPU_FLUSH_CACHES(l2, lsc, > other)); > @@ -345,8 +365,10 @@ int panthor_gpu_flush_caches(struct panthor_device > *ptdev, > } > spin_unlock_irqrestore(&ptdev->gpu->reqs_lock, flags); > > - if (ret) > + if (ret) { > + panthor_gpu_emit_flush_caches_tp(ptdev, start, l2, lsc, other, > ret); > return ret; > + } > > if (!wait_event_timeout(ptdev->gpu->reqs_acked, > !(ptdev->gpu->pending_reqs & > GPU_IRQ_CLEAN_CACHES_COMPLETED), > @@ -360,6 +382,8 @@ int panthor_gpu_flush_caches(struct panthor_device *ptdev, > spin_unlock_irqrestore(&ptdev->gpu->reqs_lock, flags); > } > > + panthor_gpu_emit_flush_caches_tp(ptdev, start, l2, lsc, other, ret); > + > if (ret) { > panthor_device_schedule_reset(ptdev); > drm_err(&ptdev->base, "Flush caches timeout"); > diff --git a/drivers/gpu/drm/panthor/panthor_trace.h > b/drivers/gpu/drm/panthor/panthor_trace.h > index 6ffeb4fe6599..bd8652549ab4 100644 > --- a/drivers/gpu/drm/panthor/panthor_trace.h > +++ b/drivers/gpu/drm/panthor/panthor_trace.h > @@ -76,6 +76,44 @@ TRACE_EVENT(gpu_job_irq, > __entry->events, __entry->duration_ns) > ); > > +/** > + * gpu_cache_flush - emitted after cache flush completes > + * @dev: pointer to the &struct device, for printing the device name > + * @l2: "l2" flush flags > + * @lsc: "lsc" flush flags > + * @other: "other" flush flags > + * @duration_ns: how long the cache flush operation took, in nanoseconds > + * @ret: return status, 0 == success, negative errno on error > + * > + * Begins measuring after any initial lock contention around the locks needed > + * for flushing caches, but before the actual cache flush is requested. Stops > + * measuring and is emitted after flush operation is over. > + */ > +TRACE_EVENT(gpu_cache_flush, > + TP_PROTO(const struct device *dev, u32 l2, u32 lsc, u32 other, > + u32 duration_ns, int ret), > + TP_ARGS(dev, l2, lsc, other, duration_ns, ret), > + TP_STRUCT__entry( > + __string(dev_name, dev_name(dev)) > + __field(u32, l2) > + __field(u32, lsc) > + __field(u32, other) > + __field(u32, duration_ns) > + __field(int, ret) > + ), > + TP_fast_assign( > + __assign_str(dev_name); > + __entry->l2 = l2; > + __entry->lsc = lsc; > + __entry->other = other; > + __entry->duration_ns = duration_ns; > + __entry->ret = ret; > + ), > + TP_printk("%s: l2=0x%x lsc=0x%x other=0x%x duration_ns=%u ret=%d", > + __get_str(dev_name), __entry->l2, __entry->lsc, > + __entry->other, __entry->duration_ns, __entry->ret) > +); > + > #endif /* __PANTHOR_TRACE_H__ */ > > #undef TRACE_INCLUDE_PATH >
