From: "Clément Péron" <peron.clem@gmail.com> To: Robin Murphy <robin.murphy@arm.com> Cc: 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>, linux-kernel <linux-kernel@vger.kernel.org>, dri-devel <dri-devel@lists.freedesktop.org> Subject: Re: [PATCH 05/15] drm/panfrost: use spinlock instead of atomic Date: Fri, 29 May 2020 14:35:08 +0200 [thread overview] Message-ID: <CAJiuCcemwM-11ZT5+-4JfyTgTRD-_JjWz=HDCme8743M5Epf0g@mail.gmail.com> (raw) In-Reply-To: <788ac664-e426-d307-f81e-9632de09887c@arm.com> Hi Robin, On Fri, 29 May 2020 at 14:20, Robin Murphy <robin.murphy@arm.com> wrote: > > 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. I have follow the modification requested for lima devfreq and clearly don't have any argument to switch to spinlock. The Lima Maintainer asked to change witht the following reason : "Better make this count a normal int which is also protected by the spinlock, because current implementation can't protect atomic ops for state change and busy idle check and we are using spinlock already" > > > 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. It's copy/paste from lima I will update it, > > Given that, should this actually be considered a fix for 9e62b885f715 > ("drm/panfrost: Simplify devfreq utilisation tracking")? I can't say if it can be considered as a fix, I didn't see any improvement on my board before and after this patch. I'm still facing some issue and didn't have time to fully investigate it. Thanks for you review, > > Robin.
WARNING: multiple messages have this Message-ID (diff)
From: "Clément Péron" <peron.clem@gmail.com> To: Robin Murphy <robin.murphy@arm.com> Cc: Nishanth Menon <nm@ti.com>, Tomeu Vizoso <tomeu.vizoso@collabora.com>, Stephen Boyd <sboyd@kernel.org>, Viresh Kumar <vireshk@kernel.org>, dri-devel <dri-devel@lists.freedesktop.org>, linux-kernel <linux-kernel@vger.kernel.org>, Steven Price <steven.price@arm.com>, Chen-Yu Tsai <wens@csie.org>, Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> Subject: Re: [PATCH 05/15] drm/panfrost: use spinlock instead of atomic Date: Fri, 29 May 2020 14:35:08 +0200 [thread overview] Message-ID: <CAJiuCcemwM-11ZT5+-4JfyTgTRD-_JjWz=HDCme8743M5Epf0g@mail.gmail.com> (raw) In-Reply-To: <788ac664-e426-d307-f81e-9632de09887c@arm.com> Hi Robin, On Fri, 29 May 2020 at 14:20, Robin Murphy <robin.murphy@arm.com> wrote: > > 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. I have follow the modification requested for lima devfreq and clearly don't have any argument to switch to spinlock. The Lima Maintainer asked to change witht the following reason : "Better make this count a normal int which is also protected by the spinlock, because current implementation can't protect atomic ops for state change and busy idle check and we are using spinlock already" > > > 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. It's copy/paste from lima I will update it, > > Given that, should this actually be considered a fix for 9e62b885f715 > ("drm/panfrost: Simplify devfreq utilisation tracking")? I can't say if it can be considered as a fix, I didn't see any improvement on my board before and after this patch. I'm still facing some issue and didn't have time to fully investigate it. Thanks for you review, > > Robin. _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-05-29 12:35 UTC|newest] Thread overview: 72+ 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 ` Clément Péron 2020-05-10 16:55 ` [PATCH 01/15] drm/panfrost: avoid static declaration Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-10 16:55 ` [PATCH 02/15] drm/panfrost: clean headers in devfreq Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 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 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-10 16:55 ` [PATCH 04/15] drm/panfrost: introduce panfrost_devfreq struct Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-10 16:55 ` [PATCH 05/15] drm/panfrost: use spinlock instead of atomic Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-29 12:20 ` Robin Murphy 2020-05-29 12:20 ` Robin Murphy 2020-05-29 12:35 ` Clément Péron [this message] 2020-05-29 12:35 ` Clément Péron 2020-05-29 12:47 ` Steven Price 2020-05-29 12:47 ` Steven Price 2020-05-10 16:55 ` [PATCH 06/15] drm/panfrost: properly handle error in probe Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 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 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-29 12:45 ` Clément Péron 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 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-29 12:38 ` Clément Péron 2020-05-29 12:38 ` Clément Péron 2020-06-08 11:55 ` Tomeu Vizoso 2020-06-08 11:55 ` Tomeu Vizoso 2020-05-10 16:55 ` [PATCH 09/15] drm/panfrost: dynamically alloc regulators Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:22 ` Steven Price 2020-05-28 13:22 ` Steven Price 2020-05-10 16:55 ` [PATCH 10/15] drm/panfrost: add regulators to devfreq Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:23 ` Steven Price 2020-05-28 13:23 ` Steven Price 2020-05-29 12:37 ` Clément Péron 2020-05-29 12:37 ` Clément Péron 2020-05-10 16:55 ` [PATCH 11/15] drm/panfrost: set devfreq clock name Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-28 13:23 ` Steven Price 2020-05-28 13:23 ` Steven Price 2020-05-29 12:35 ` Clément Péron 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 ` 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 ` 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 ` Clément Péron 2020-05-10 16:55 ` [PATCH 15/15] [DO NOT MERGE] arm64: dts: allwinner: force GPU regulator to be always Clément Péron 2020-05-10 16:55 ` Clément Péron 2020-05-11 5:43 ` [PATCH 00/15][RFC] Add regulator devfreq support to Panfrost Tomeu Vizoso 2020-05-11 5:43 ` Tomeu Vizoso
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