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From: Guenter Roeck <linux@roeck-us.net>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Russell King <linux@arm.linux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Subject: Re: [PATCH 3/6] ARM: PSCI: Register with kernel restart handler
Date: Wed, 13 Apr 2016 17:42:23 -0700	[thread overview]
Message-ID: <20160414004223.GA18564@roeck-us.net> (raw)
In-Reply-To: <CAMuHMdU+vj4HDTLdXngUsTjF-Ki-HtbhoRU6mV7UKCz-BhFAtQ@mail.gmail.com>

On Wed, Apr 13, 2016 at 03:22:44PM +0200, Geert Uytterhoeven wrote:
> On Wed, Apr 13, 2016 at 3:10 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> > On 04/13/2016 04:05 AM, Mark Rutland wrote:
> >> On Fri, Apr 08, 2016 at 05:53:56AM -0700, Guenter Roeck wrote:
> >>>
> >>> Register with kernel restart handler instead of setting arm_pm_restart
> >>> directly. This enables support for replacing the PSCI restart handler
> >>> with a different handler if necessary for a specific board.
> >>>
> >>> Select a priority of 129 to indicate a higher than default priority, but
> >>> keep it as low as possible since PSCI reset is known to fail on some
> >>> boards.
> >>
> >> For reference, which boards?
> >>
> > Salvator-X, reported by Geert Uytterhoeven. Wolfram Sang also reported
> > that it is broken on a board he is using, but I don't recall if it is
> > the same board.
> 
> Yes it is.
> 
> >> It's unfortunate that that a PSCI 0.2+ implementation would be lacking a
> >> working SYSTEM_RESET implementation, and it's certainly a mistake to
> >> discourage.
> >>
> >>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> >>> ---
> >>> It might make sense to introduce a restart-priority property for
> >>> devicetree
> >>> based configurations, but I am not sure if this would be acceptable.
> >>
> >>> From the DT side, I'm not keen on properties for priorities. They're
> >> incredibly fragile and don't really encode a HW property.
> >>
> > Depends. It is a convenient means to say "primary restart method" or
> > "may be broken".
> 
> The issue is supposed to be fixed in a more recent firmware, which I still have
> to try.
> 
> DT indeed isn't the right place to work around this. What we need is a
> blacklist of bad firmware versions...
> Or Perfect Firmware from Day One on (like Perfect DT from Day One ;-)
> 
That makes things quite tricky. Best I can think of is a series of boolean
devicetree properties, such as

	broken-reset-handler
	last-resort-restart-handler
	secondary-restart-handler
	default-restart-handler
	primary-restart-handler

which ends up being quite similar to the 'restart-priority' property. I'll
do this as follow-up patch, though - I do not see the point holding up the
series for this, and it is really a separate problem. I'll send rev2 with
the various Acked-by: and Reviewed-by: tags as well as the variable rename
suggested by Wolfram.

Thanks,
Guenter

WARNING: multiple messages have this Message-ID
From: linux@roeck-us.net (Guenter Roeck)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/6] ARM: PSCI: Register with kernel restart handler
Date: Wed, 13 Apr 2016 17:42:23 -0700	[thread overview]
Message-ID: <20160414004223.GA18564@roeck-us.net> (raw)
In-Reply-To: <CAMuHMdU+vj4HDTLdXngUsTjF-Ki-HtbhoRU6mV7UKCz-BhFAtQ@mail.gmail.com>

On Wed, Apr 13, 2016 at 03:22:44PM +0200, Geert Uytterhoeven wrote:
> On Wed, Apr 13, 2016 at 3:10 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> > On 04/13/2016 04:05 AM, Mark Rutland wrote:
> >> On Fri, Apr 08, 2016 at 05:53:56AM -0700, Guenter Roeck wrote:
> >>>
> >>> Register with kernel restart handler instead of setting arm_pm_restart
> >>> directly. This enables support for replacing the PSCI restart handler
> >>> with a different handler if necessary for a specific board.
> >>>
> >>> Select a priority of 129 to indicate a higher than default priority, but
> >>> keep it as low as possible since PSCI reset is known to fail on some
> >>> boards.
> >>
> >> For reference, which boards?
> >>
> > Salvator-X, reported by Geert Uytterhoeven. Wolfram Sang also reported
> > that it is broken on a board he is using, but I don't recall if it is
> > the same board.
> 
> Yes it is.
> 
> >> It's unfortunate that that a PSCI 0.2+ implementation would be lacking a
> >> working SYSTEM_RESET implementation, and it's certainly a mistake to
> >> discourage.
> >>
> >>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> >>> ---
> >>> It might make sense to introduce a restart-priority property for
> >>> devicetree
> >>> based configurations, but I am not sure if this would be acceptable.
> >>
> >>> From the DT side, I'm not keen on properties for priorities. They're
> >> incredibly fragile and don't really encode a HW property.
> >>
> > Depends. It is a convenient means to say "primary restart method" or
> > "may be broken".
> 
> The issue is supposed to be fixed in a more recent firmware, which I still have
> to try.
> 
> DT indeed isn't the right place to work around this. What we need is a
> blacklist of bad firmware versions...
> Or Perfect Firmware from Day One on (like Perfect DT from Day One ;-)
> 
That makes things quite tricky. Best I can think of is a series of boolean
devicetree properties, such as

	broken-reset-handler
	last-resort-restart-handler
	secondary-restart-handler
	default-restart-handler
	primary-restart-handler

which ends up being quite similar to the 'restart-priority' property. I'll
do this as follow-up patch, though - I do not see the point holding up the
series for this, and it is really a separate problem. I'll send rev2 with
the various Acked-by: and Reviewed-by: tags as well as the variable rename
suggested by Wolfram.

Thanks,
Guenter

  reply	other threads:[~2016-04-14  0:42 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-08 12:53 [PATCH 0/6] ARM/ARM64: Drop arm_pm_restart Guenter Roeck
2016-04-08 12:53 ` Guenter Roeck
2016-04-08 12:53 ` [PATCH 1/6] ARM: prima2: Register with kernel restart handler Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-08 12:53 ` [PATCH 2/6] ARM: xen: " Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-08 15:22   ` Konrad Rzeszutek Wilk
2016-04-08 18:20     ` Guenter Roeck
2016-04-08 18:20     ` [Xen-devel] " Guenter Roeck
2016-04-08 18:20       ` Guenter Roeck
2016-04-09 23:46   ` Stefano Stabellini
2016-04-09 23:46     ` Stefano Stabellini
2016-04-09 23:56     ` Stefano Stabellini
2016-04-09 23:56       ` Stefano Stabellini
2016-04-09 23:56     ` Stefano Stabellini
2016-04-09 23:46   ` Stefano Stabellini
2016-04-08 12:53 ` [PATCH 3/6] ARM: PSCI: " Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-12 15:36   ` Wolfram Sang
2016-04-12 15:36     ` Wolfram Sang
2016-04-13 11:05   ` Mark Rutland
2016-04-13 11:05     ` Mark Rutland
2016-04-13 11:24     ` Jisheng Zhang
2016-04-13 11:24       ` Jisheng Zhang
2016-04-13 13:10     ` Guenter Roeck
2016-04-13 13:10       ` Guenter Roeck
2016-04-13 13:22       ` Geert Uytterhoeven
2016-04-13 13:22         ` Geert Uytterhoeven
2016-04-14  0:42         ` Guenter Roeck [this message]
2016-04-14  0:42           ` Guenter Roeck
2016-04-14  8:52           ` Wolfram Sang
2016-04-14  8:52             ` Wolfram Sang
2016-04-14 13:21             ` Guenter Roeck
2016-04-14 13:21               ` Guenter Roeck
2016-04-14 14:31               ` Wolfram Sang
2016-04-14 14:31                 ` Wolfram Sang
2016-04-08 12:53 ` [PATCH 4/6] ARM: " Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-08 12:53 ` [PATCH 5/6] ARM64: Remove arm_pm_restart Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-12 13:10   ` Catalin Marinas
2016-04-12 13:10     ` Catalin Marinas
2016-04-08 12:53 ` [PATCH 6/6] ARM: " Guenter Roeck
2016-04-08 12:53   ` Guenter Roeck
2016-04-08 15:44 ` [PATCH 0/6] ARM/ARM64: Drop arm_pm_restart Wolfram Sang
2016-04-08 15:44   ` Wolfram Sang
2016-04-08 20:46 ` Arnd Bergmann
2016-04-08 20:46   ` Arnd Bergmann
2016-04-12 15:41 ` Wolfram Sang
2016-04-12 15:41   ` Wolfram Sang

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