From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9DA5533E36F for ; Fri, 16 Jan 2026 15:56:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768579019; cv=none; b=aDWURc2IqQjx3/cK9TaFOvzkCyNx5F5jDvhwJGQpaOGdkiXAukHDgX08FiwROWNVe6TIi7/egYNDJhZOAdvJ8P45yAB+/2rJQIzf3JuluX94Nswp+Zz07k0RdomAnkOkxQjYpO1UBkNC0JUCHT0zuN8hDKr4UdgnhAXqp40YZEk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768579019; c=relaxed/simple; bh=FxVqyGge+tHOh//NeS6soBGy26KvqlHGlig431CAW9A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RkYM81OFa/EGmhOmzxJS72NfYX37au2Ew7cGZ3Ii9J6joLCr03wxXZ1nmUqoJEQ++0IKDn+bTSuFWfCT8oEx3aCZ4h48ArB1T7qN+TN8arReZeqi3KSitdO3Ub7UWzgsrtvNuHZiwbJ1Dvg3WGY5JcIkBTM/ItEBGzl2hnShQiY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 81A161516; Fri, 16 Jan 2026 07:56:48 -0800 (PST) Received: from [10.1.27.18] (e122027.cambridge.arm.com [10.1.27.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 97D0A3F632; Fri, 16 Jan 2026 07:56:52 -0800 (PST) Message-ID: <47edc01d-027f-4c61-9e84-3f1ee599911f@arm.com> Date: Fri, 16 Jan 2026 15:56:52 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 4/4] drm/panthor: Add gpu_job_irq tracepoint To: Nicolas Frattaroli , Boris Brezillon , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Chia-I Wu , Karunika Choo Cc: kernel@collabora.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org References: <20260116-panthor-tracepoints-v10-0-d925986e3d1b@collabora.com> <20260116-panthor-tracepoints-v10-4-d925986e3d1b@collabora.com> From: Steven Price Content-Language: en-GB In-Reply-To: <20260116-panthor-tracepoints-v10-4-d925986e3d1b@collabora.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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 Reviewed-by: Steven Price > --- > 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 >