From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2437B276058 for ; Fri, 16 Jan 2026 13:59:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768571989; cv=none; b=d9HLvQH6YzUV30sewfMW4XYTyQ3KwtFG4fkiBhh+Ybtd2hLM7/b1GxUQo7ezzhr65cUCVAwstr5Td7ejHDAOaHcYWtVLoNCeOks40fncjGe2VZixdKkyZvodbcGW6UE1DOXjtJTBLXscTH3HWZpSvO9yjD4X2vpV5LHlBRsFVM0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768571989; c=relaxed/simple; bh=V7U6K2dsEJQaHL/31dkTPMbO8MSt1XoJAe59br6MtZ0=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=RBfWZKj0F0sQEWLUhHOOeVaUdxl8qIAf9u05oMBfN2qMc69c1cz46VdhExRUxwKb7bwSP+9NrXJuLLz7maAubT82w4i8NldqrYGtmNYEkRqnEHnb/X+KYAFr55OVGeA72p3S1s6tLz6RDfRfoOr66hMgSax4aXuRV8iwC31Y/T4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=AmuuAZRK; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="AmuuAZRK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1768571985; bh=V7U6K2dsEJQaHL/31dkTPMbO8MSt1XoJAe59br6MtZ0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=AmuuAZRKkLae5OyBHd8Lwo97uktMT/VM+oOZesH5y9dixbVKNk6/hGIges9HYqYyt XJA58WlH+AZOAw5GN6KKvSVo5yIMTYBgavQMW6k1mE3/v3O/ZhCzpvIW5gQ6T81a10 8JfSd+flU3N2IVh2ajE6uxvXCmqyJfyx7HZD+3G2p08M0NzdU2x89rHTktwVOkJBl7 7aNgIFXvVsq0hnMMcOZ0zMld9VpM65ChlrfIwy2ivprBaWN22t2gERzNe6t6Tf+BDa fdAHttQteVMqaxVf+KT88J+ESQRldoV7zoU4FhUSIfv6AxX8zc9o/p3O/SUczzohIz L3l8GsNakCE2A== Received: from fedora (unknown [IPv6:2a01:e0a:2c:6930:d919:a6e:5ea1:8a9f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id E35C817E0443; Fri, 16 Jan 2026 14:59:44 +0100 (CET) Date: Fri, 16 Jan 2026 14:59:40 +0100 From: Boris Brezillon To: Nicolas Frattaroli Cc: Steven Price , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Chia-I Wu , Karunika Choo , kernel@collabora.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH v10 3/4] drm/panthor: Add tracepoint for hardware utilisation changes Message-ID: <20260116145940.6627ea42@fedora> In-Reply-To: <20260116-panthor-tracepoints-v10-3-d925986e3d1b@collabora.com> References: <20260116-panthor-tracepoints-v10-0-d925986e3d1b@collabora.com> <20260116-panthor-tracepoints-v10-3-d925986e3d1b@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 16 Jan 2026 13:57:32 +0100 Nicolas Frattaroli wrote: > Mali GPUs have three registers that indicate which parts of the hardware > are powered at any moment. These take the form of bitmaps. In the case > of SHADER_READY for example, a high bit indicates that the shader core > corresponding to that bit index is powered on. These bitmaps aren't > solely contiguous bits, as it's common to have holes in the sequence of > shader core indices, and the actual set of which cores are present is > defined by the "shader present" register. > > When the GPU finishes a power state transition, it fires a > GPU_IRQ_POWER_CHANGED_ALL interrupt. After such an interrupt is > received, the _READY registers will contain new interesting data. During > power transitions, the GPU_IRQ_POWER_CHANGED interrupt will fire, and > the registers will likewise contain potentially changed data. > > This is not to be confused with the PWR_IRQ_POWER_CHANGED_ALL interrupt, > which is something related to Mali v14+'s power control logic. The > _READY registers and corresponding interrupts are already available in > v9 and onwards. > > Expose the data as a tracepoint to userspace. This allows users to debug > various scenarios and gather interesting information, such as: knowing > how much hardware is lit up at any given time, correlating graphics > corruption with a specific powered shader core, measuring when hardware > is allowed to go to a powered off state again, and so on. > > The registration/unregistration functions for the tracepoint go through > a wrapper in panthor_hw.c, so that v14+ can implement the same > tracepoint by adding its hardware specific IRQ on/off callbacks to the > panthor_hw.ops member. > > Signed-off-by: Nicolas Frattaroli > --- > drivers/gpu/drm/panthor/panthor_gpu.c | 28 +++++++++++++++ > 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_trace.h | 58 ++++++++++++++++++++++++++++++ > 5 files changed, 158 insertions(+) > > diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c > index 9304469a711a..2ab444ee8c71 100644 > --- a/drivers/gpu/drm/panthor/panthor_gpu.c > +++ b/drivers/gpu/drm/panthor/panthor_gpu.c > @@ -22,6 +22,9 @@ > #include "panthor_hw.h" > #include "panthor_regs.h" > > +#define CREATE_TRACE_POINTS > +#include "panthor_trace.h" > + > /** > * struct panthor_gpu - GPU block management data. > */ > @@ -48,6 +51,9 @@ struct panthor_gpu { > GPU_IRQ_RESET_COMPLETED | \ > GPU_IRQ_CLEAN_CACHES_COMPLETED) > > +#define GPU_POWER_INTERRUPTS_MASK \ > + (GPU_IRQ_POWER_CHANGED | GPU_IRQ_POWER_CHANGED_ALL) > + > static void panthor_gpu_coherency_set(struct panthor_device *ptdev) > { > gpu_write(ptdev, GPU_COHERENCY_PROTOCOL, > @@ -80,6 +86,12 @@ static void panthor_gpu_irq_handler(struct panthor_device *ptdev, u32 status) > { > gpu_write(ptdev, GPU_INT_CLEAR, status); > > + if (tracepoint_enabled(gpu_power_status) && (status & GPU_POWER_INTERRUPTS_MASK)) > + trace_gpu_power_status(ptdev->base.dev, > + gpu_read64(ptdev, SHADER_READY), > + gpu_read64(ptdev, TILER_READY), > + gpu_read64(ptdev, L2_READY)); > + > if (status & GPU_IRQ_FAULT) { > u32 fault_status = gpu_read(ptdev, GPU_FAULT_STATUS); > u64 address = gpu_read64(ptdev, GPU_FAULT_ADDR); > @@ -157,6 +169,22 @@ int panthor_gpu_init(struct panthor_device *ptdev) > return 0; > } > > +int panthor_gpu_power_changed_on(struct panthor_device *ptdev) > +{ > + guard(pm_runtime_active)(ptdev->base.dev); > + > + panthor_gpu_irq_enable_events(&ptdev->gpu->irq, GPU_POWER_INTERRUPTS_MASK); > + > + return 0; > +} > + > +void panthor_gpu_power_changed_off(struct panthor_device *ptdev) > +{ > + guard(pm_runtime_active)(ptdev->base.dev); > + > + panthor_gpu_irq_disable_events(&ptdev->gpu->irq, GPU_POWER_INTERRUPTS_MASK); > +} > + > /** > * panthor_gpu_block_power_off() - Power-off a specific block of the GPU > * @ptdev: Device. > diff --git a/drivers/gpu/drm/panthor/panthor_gpu.h b/drivers/gpu/drm/panthor/panthor_gpu.h > index 12e66f48ced1..12c263a39928 100644 > --- a/drivers/gpu/drm/panthor/panthor_gpu.h > +++ b/drivers/gpu/drm/panthor/panthor_gpu.h > @@ -51,5 +51,7 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev); > int panthor_gpu_flush_caches(struct panthor_device *ptdev, > u32 l2, u32 lsc, u32 other); > int panthor_gpu_soft_reset(struct panthor_device *ptdev); > +void panthor_gpu_power_changed_off(struct panthor_device *ptdev); > +int panthor_gpu_power_changed_on(struct panthor_device *ptdev); > > #endif > diff --git a/drivers/gpu/drm/panthor/panthor_hw.c b/drivers/gpu/drm/panthor/panthor_hw.c > index 80c521784cd3..d135aa6724fa 100644 > --- a/drivers/gpu/drm/panthor/panthor_hw.c > +++ b/drivers/gpu/drm/panthor/panthor_hw.c > @@ -2,6 +2,8 @@ > /* Copyright 2025 ARM Limited. All rights reserved. */ > > #include > +#include > + > #include > > #include "panthor_device.h" > @@ -30,6 +32,8 @@ static struct panthor_hw panthor_hw_arch_v10 = { > .soft_reset = panthor_gpu_soft_reset, > .l2_power_off = panthor_gpu_l2_power_off, > .l2_power_on = panthor_gpu_l2_power_on, > + .power_changed_off = panthor_gpu_power_changed_off, > + .power_changed_on = panthor_gpu_power_changed_on, > }, > }; > > @@ -54,6 +58,64 @@ static struct panthor_hw_entry panthor_hw_match[] = { > }, > }; > > +static int panthor_hw_set_power_tracing(struct device *dev, void *data) > +{ > + struct panthor_device *ptdev = dev_get_drvdata(dev); > + > + if (!ptdev) > + return -ENODEV; > + > + if (!ptdev->hw) > + return 0; > + > + if (data) { > + if (ptdev->hw->ops.power_changed_on) > + return ptdev->hw->ops.power_changed_on(ptdev); > + } else { > + if (ptdev->hw->ops.power_changed_off) > + ptdev->hw->ops.power_changed_off(ptdev); > + } > + > + return 0; > +} nit: since you've already exposed the power transition monitoring through two different callbacks, could we also do the same here, with two panthor_hw_power_tracing_{on,off}() functions which ignore the data (not a huge fan of this bool->pointer cast). static int panthor_hw_power_tracing_on(struct device *dev, void *data) { struct panthor_device *ptdev = dev_get_drvdata(dev); if (!ptdev) return -ENODEV; if (ptdev->hw && ptdev->hw->ops.power_changed_on) return ptdev->hw->ops.power_changed_on(ptdev); return 0; } static int panthor_hw_power_tracing_off(struct device *dev, void *data) { struct panthor_device *ptdev = dev_get_drvdata(dev); if (!ptdev) return -ENODEV; if (ptdev->hw && ptdev->hw->ops.power_changed_off) return ptdev->hw->ops.power_changed_off(ptdev); return 0; } Feel free to ignore, this patch is Reviewed-by: Boris Brezillon regardless. > + > +int panthor_hw_power_status_register(void) > +{ > + struct device_driver *drv; > + int ret; > + > + drv = driver_find("panthor", &platform_bus_type); > + if (!drv) > + return -ENODEV; > + > + ret = driver_for_each_device(drv, NULL, (void *)true, > + panthor_hw_set_power_tracing); > + > + return ret; > +} > + > +void panthor_hw_power_status_unregister(void) > +{ > + struct device_driver *drv; > + int ret; > + > + drv = driver_find("panthor", &platform_bus_type); > + if (!drv) > + return; > + > + ret = driver_for_each_device(drv, NULL, NULL, panthor_hw_set_power_tracing); > + > + /* > + * Ideally, it'd be possible to ask driver_for_each_device to hand us > + * another "start" to keep going after the failing device, but it > + * doesn't do that. Minor inconvenience in what is probably a bad day > + * on the computer already though. > + */ > + if (ret) > + pr_warn("Couldn't mask power IRQ for at least one device: %pe\n", > + ERR_PTR(ret)); > +} > + > static char *get_gpu_model_name(struct panthor_device *ptdev) > { > const u32 gpu_id = ptdev->gpu_info.gpu_id; > diff --git a/drivers/gpu/drm/panthor/panthor_hw.h b/drivers/gpu/drm/panthor/panthor_hw.h > index 56c68c1e9c26..2c28aea82841 100644 > --- a/drivers/gpu/drm/panthor/panthor_hw.h > +++ b/drivers/gpu/drm/panthor/panthor_hw.h > @@ -19,6 +19,12 @@ struct panthor_hw_ops { > > /** @l2_power_on: L2 power on function pointer */ > int (*l2_power_on)(struct panthor_device *ptdev); > + > + /** @power_changed_on: Start listening to power change IRQs */ > + int (*power_changed_on)(struct panthor_device *ptdev); > + > + /** @power_changed_off: Stop listening to power change IRQs */ > + void (*power_changed_off)(struct panthor_device *ptdev); > }; > > /** > @@ -32,6 +38,8 @@ struct panthor_hw { > }; > > int panthor_hw_init(struct panthor_device *ptdev); > +int panthor_hw_power_status_register(void); > +void panthor_hw_power_status_unregister(void); > > static inline int panthor_hw_soft_reset(struct panthor_device *ptdev) > { > diff --git a/drivers/gpu/drm/panthor/panthor_trace.h b/drivers/gpu/drm/panthor/panthor_trace.h > new file mode 100644 > index 000000000000..5bd420894745 > --- /dev/null > +++ b/drivers/gpu/drm/panthor/panthor_trace.h > @@ -0,0 +1,58 @@ > +/* 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 > +#include > + > +#include "panthor_hw.h" > + > +/** > + * gpu_power_status - called whenever parts of GPU hardware are turned on or off > + * @dev: pointer to the &struct device, for printing the device name > + * @shader_bitmap: bitmap where a high bit indicates the shader core at a given > + * bit index is on, and a low bit indicates a shader core is > + * either powered off or absent > + * @tiler_bitmap: bitmap where a high bit indicates the tiler unit at a given > + * bit index is on, and a low bit indicates a tiler unit is > + * either powered off or absent > + * @l2_bitmap: bitmap where a high bit indicates the L2 cache at a given bit > + * index is on, and a low bit indicates the L2 cache is either > + * powered off or absent > + */ > +TRACE_EVENT_FN(gpu_power_status, > + TP_PROTO(const struct device *dev, u64 shader_bitmap, u64 tiler_bitmap, > + u64 l2_bitmap), > + TP_ARGS(dev, shader_bitmap, tiler_bitmap, l2_bitmap), > + TP_STRUCT__entry( > + __string(dev_name, dev_name(dev)) > + __field(u64, shader_bitmap) > + __field(u64, tiler_bitmap) > + __field(u64, l2_bitmap) > + ), > + TP_fast_assign( > + __assign_str(dev_name); > + __entry->shader_bitmap = shader_bitmap; > + __entry->tiler_bitmap = tiler_bitmap; > + __entry->l2_bitmap = l2_bitmap; > + ), > + TP_printk("%s: shader_bitmap=0x%llx tiler_bitmap=0x%llx l2_bitmap=0x%llx", > + __get_str(dev_name), __entry->shader_bitmap, __entry->tiler_bitmap, > + __entry->l2_bitmap > + ), > + panthor_hw_power_status_register, panthor_hw_power_status_unregister > +); > + > +#endif /* __PANTHOR_TRACE_H__ */ > + > +#undef TRACE_INCLUDE_PATH > +#define TRACE_INCLUDE_PATH . > +#undef TRACE_INCLUDE_FILE > +#define TRACE_INCLUDE_FILE panthor_trace > + > +#include >