linux-kernel - Re: [PATCH 1/2] drm/panthor: Add tracepoint for hardware utilisation changes

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Message-ID: <3726594.R56niFO833@workhorse>
Date: Tue, 09 Dec 2025 14:01:23 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Boris Brezillon <boris.brezillon@...labora.com>,
 Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Karunika Choo <karunika.choo@....com>
Cc: kernel@...labora.com, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org
Subject:
 Re: [PATCH 1/2] drm/panthor: Add tracepoint for hardware utilisation changes

On Monday, 8 December 2025 18:14:53 Central European Standard Time Karunika Choo wrote:
> On 03/12/2025 13:56, Nicolas Frattaroli wrote:
> > [... snip ...]
> > 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),
> 
> nit: if you want to add tracing can we also add the device name as
> well? Something like:
> 
>   TP_PROTO(struct device *dev, ...),
>   TP_ARGS(dev, ...),
>   TP_STRUCT__ENTRY(
>           __string(dev_name, dev_name(dev))
>           ...
>   ).
>   ...

This is a great idea, will do. Any specific reason to pass the
device in the tracepoint rather than a const char*?

> 
> This will help differentiate the device it is originating from in
> a multi GPU situation.

I'll try not to get too excited at the prospect of systems using
multiple Mali GPUs because I know the likeliest case this happens
on is Arm evaluation systems with a hard IP and a soft IP loaded to
the FPGA core. :)

Kind regards,
Nicolas Frattaroli

> 
> Kind regards,
> Karunika
> 
> > +	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>
> > 
> 
> 
>