From: Robin Murphy <robin.murphy@arm.com>
To: "Clément Péron" <peron.clem@gmail.com>,
"Rob Herring" <robh@kernel.org>,
"Tomeu Vizoso" <tomeu.vizoso@collabora.com>,
"Steven Price" <steven.price@arm.com>,
"Alyssa Rosenzweig" <alyssa.rosenzweig@collabora.com>,
"Viresh Kumar" <vireshk@kernel.org>, "Nishanth Menon" <nm@ti.com>,
"Stephen Boyd" <sboyd@kernel.org>,
"Maxime Ripard" <mripard@kernel.org>,
"Chen-Yu Tsai" <wens@csie.org>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 05/15] drm/panfrost: use spinlock instead of atomic
Date: Fri, 29 May 2020 13:20:24 +0100 [thread overview]
Message-ID: <788ac664-e426-d307-f81e-9632de09887c@arm.com> (raw)
In-Reply-To: <20200510165538.19720-6-peron.clem@gmail.com>
On 2020-05-10 17:55, Clément Péron wrote:
> Convert busy_count to a simple int protected by spinlock.
A little more reasoning might be nice.
> Signed-off-by: Clément Péron <peron.clem@gmail.com>
> ---
[...]
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.h b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> index 0697f8d5aa34..e6629900a618 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> @@ -4,6 +4,7 @@
> #ifndef __PANFROST_DEVFREQ_H__
> #define __PANFROST_DEVFREQ_H__
>
> +#include <linux/spinlock.h>
> #include <linux/ktime.h>
>
> struct devfreq;
> @@ -14,10 +15,17 @@ struct panfrost_device;
> struct panfrost_devfreq {
> struct devfreq *devfreq;
> struct thermal_cooling_device *cooling;
> +
> ktime_t busy_time;
> ktime_t idle_time;
> ktime_t time_last_update;
> - atomic_t busy_count;
> + int busy_count;
> + /*
> + * Protect busy_time, idle_time, time_last_update and busy_count
> + * because these can be updated concurrently, for example by the GP
> + * and PP interrupts.
> + */
Nit: this comment is clearly wrong, since we only have Job, GPU and MMU
interrupts here. I guess if there is a race it would be between
submission/completion/timeout on different job slots.
Given that, should this actually be considered a fix for 9e62b885f715
("drm/panfrost: Simplify devfreq utilisation tracking")?
Robin.
next prev parent reply other threads:[~2020-05-29 12:20 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-10 16:55 [PATCH 00/15][RFC] Add regulator devfreq support to Panfrost Clément Péron
2020-05-10 16:55 ` [PATCH 01/15] drm/panfrost: avoid static declaration Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-10 16:55 ` [PATCH 02/15] drm/panfrost: clean headers in devfreq Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-10 16:55 ` [PATCH 03/15] drm/panfrost: don't use pfdevfreq.busy_count to know if hw is idle Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-10 16:55 ` [PATCH 04/15] drm/panfrost: introduce panfrost_devfreq struct Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-10 16:55 ` [PATCH 05/15] drm/panfrost: use spinlock instead of atomic Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-29 12:20 ` Robin Murphy [this message]
2020-05-29 12:35 ` Clément Péron
2020-05-29 12:47 ` Steven Price
2020-05-10 16:55 ` [PATCH 06/15] drm/panfrost: properly handle error in probe Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-10 16:55 ` [PATCH 07/15] drm/panfrost: use device_property_present to check for OPP Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-29 12:45 ` Clément Péron
2020-05-10 16:55 ` [PATCH 08/15] drm/panfrost: move devfreq_init()/fini() in device Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-29 12:38 ` Clément Péron
2020-06-08 11:55 ` Tomeu Vizoso
2020-05-10 16:55 ` [PATCH 09/15] drm/panfrost: dynamically alloc regulators Clément Péron
2020-05-28 13:22 ` Steven Price
2020-05-10 16:55 ` [PATCH 10/15] drm/panfrost: add regulators to devfreq Clément Péron
2020-05-28 13:23 ` Steven Price
2020-05-29 12:37 ` Clément Péron
2020-05-10 16:55 ` [PATCH 11/15] drm/panfrost: set devfreq clock name Clément Péron
2020-05-28 13:23 ` Steven Price
2020-05-29 12:35 ` Clément Péron
2020-05-10 16:55 ` [PATCH 12/15] arm64: defconfig: Enable devfreq cooling device Clément Péron
2020-05-10 16:55 ` [PATCH 13/15] arm64: dts: allwinner: h6: Add cooling map for GPU Clément Péron
2020-05-10 16:55 ` [PATCH 14/15] [DO NOT MERGE] arm64: dts: allwinner: h6: Add GPU OPP table Clément Péron
2020-05-10 16:55 ` [PATCH 15/15] [DO NOT MERGE] arm64: dts: allwinner: force GPU regulator to be always Clément Péron
2020-05-11 5:43 ` [PATCH 00/15][RFC] Add regulator devfreq support to Panfrost Tomeu Vizoso
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