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From: Arnd Bergmann <arnd@arndb.de>
To: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>,
	Russell King <linux@arm.linux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC 02/17] ARM: call clk_of_init from time_init
Date: Wed, 21 Aug 2013 20:54:10 +0200	[thread overview]
Message-ID: <201308212054.10417.arnd@arndb.de> (raw)
In-Reply-To: <5213CF58.50703@gmail.com>

On Tuesday 20 August 2013, Sebastian Hesselbarth wrote:
> Perhaps Tegra is the common case but other SoC haven't dug deep enough?
> IMHO from a HW point-of-view clocks are really among the essential
> things that need to be running before you can do anything useful.
> 
> Just consider boot loaders that run fine without irqs but don't without
> clocks (even if just represented by API). Maybe you are right, and we
> should call of_clk_init(NULL) as early as possible. That would also
> eliminate patch 1/17 as you suggest.

Timers and interrupts are also things that are required really early,
and from my experience they tend to be needed earlier than clock
management. Obviously you need some clocks to be enabled in order
to do anything (including interrupt handling), but those clocks tend
to be enabled in the boot loader, so we don't have to worry about
reprogramming them this early.

	Arnd

WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 02/17] ARM: call clk_of_init from time_init
Date: Wed, 21 Aug 2013 20:54:10 +0200	[thread overview]
Message-ID: <201308212054.10417.arnd@arndb.de> (raw)
In-Reply-To: <5213CF58.50703@gmail.com>

On Tuesday 20 August 2013, Sebastian Hesselbarth wrote:
> Perhaps Tegra is the common case but other SoC haven't dug deep enough?
> IMHO from a HW point-of-view clocks are really among the essential
> things that need to be running before you can do anything useful.
> 
> Just consider boot loaders that run fine without irqs but don't without
> clocks (even if just represented by API). Maybe you are right, and we
> should call of_clk_init(NULL) as early as possible. That would also
> eliminate patch 1/17 as you suggest.

Timers and interrupts are also things that are required really early,
and from my experience they tend to be needed earlier than clock
management. Obviously you need some clocks to be enabled in order
to do anything (including interrupt handling), but those clocks tend
to be enabled in the boot loader, so we don't have to worry about
reprogramming them this early.

	Arnd

  reply	other threads:[~2013-08-21 18:54 UTC|newest]

Thread overview: 228+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-20  2:04 [RFC 00/17] ARM: provide common arch init for DT clocks Sebastian Hesselbarth
2013-08-20  2:04 ` Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 01/17] clk: ensure __clk_of_table is only initialized once Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 02/17] ARM: call clk_of_init from time_init Sebastian Hesselbarth
2013-08-20 15:46   ` Stephen Warren
2013-08-20 15:46     ` Stephen Warren
2013-08-20 19:47     ` Sebastian Hesselbarth
2013-08-20 19:47       ` Sebastian Hesselbarth
2013-08-20 19:52       ` Stephen Warren
2013-08-20 19:52         ` Stephen Warren
2013-08-20 20:19         ` Sebastian Hesselbarth
2013-08-20 20:19           ` Sebastian Hesselbarth
2013-08-21 18:54           ` Arnd Bergmann [this message]
2013-08-21 18:54             ` Arnd Bergmann
2013-08-22  7:25             ` Mike Turquette
2013-08-22  7:25               ` Mike Turquette
2013-08-22 17:28               ` Arnd Bergmann
2013-08-22 17:28                 ` Arnd Bergmann
2013-08-20 20:44     ` Arnd Bergmann
2013-08-20 20:44       ` Arnd Bergmann
2013-08-20 20:57       ` Stephen Warren
2013-08-20 20:57         ` Stephen Warren
2013-08-21 18:51         ` Arnd Bergmann
2013-08-21 18:51           ` Arnd Bergmann
2013-08-20  2:04 ` [RFC 03/17] ARM: dove: remove custom .init_time hook Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 04/17] ARM: exynos: " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 05/17] ARM: highbank: " Sebastian Hesselbarth
2013-08-20 19:12   ` Rob Herring
2013-08-20 19:12     ` Rob Herring
2013-08-20 20:01     ` Sebastian Hesselbarth
2013-08-20 20:01       ` Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 06/17] ARM: imx: " Sebastian Hesselbarth
2013-08-20  7:26   ` Sascha Hauer
2013-08-20  7:26     ` Sascha Hauer
2013-08-20  8:48     ` Sebastian Hesselbarth
2013-08-20  8:48       ` Sebastian Hesselbarth
2013-08-20  9:10       ` Sascha Hauer
2013-08-20  9:10         ` Sascha Hauer
2013-08-20  9:20         ` Sebastian Hesselbarth
2013-08-20  9:20           ` Sebastian Hesselbarth
2013-08-20 10:20           ` Russell King - ARM Linux
2013-08-20 10:20             ` Russell King - ARM Linux
2013-08-20 10:37             ` Sebastian Hesselbarth
2013-08-20 10:37               ` Sebastian Hesselbarth
2013-08-20 10:42               ` Russell King - ARM Linux
2013-08-20 10:42                 ` Russell King - ARM Linux
2013-08-20 10:46                 ` Sebastian Hesselbarth
2013-08-20 10:46                   ` Sebastian Hesselbarth
2013-08-20  9:23   ` [RFC v2] " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 07/17] ARM: kirkwood: " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 08/17] ARM: mvebu: " Sebastian Hesselbarth
2013-08-20 12:50   ` Ezequiel Garcia
2013-08-20 12:50     ` Ezequiel Garcia
2013-08-20 13:12     ` Sebastian Hesselbarth
2013-08-20 13:12       ` Sebastian Hesselbarth
2013-08-20 14:01       ` Ezequiel Garcia
2013-08-20 14:01         ` Ezequiel Garcia
2013-08-23 10:06   ` Gregory CLEMENT
2013-08-23 10:06     ` Gregory CLEMENT
2013-08-23 10:32     ` Sebastian Hesselbarth
2013-08-23 10:32       ` Sebastian Hesselbarth
2013-08-23 11:39       ` Gregory CLEMENT
2013-08-23 11:39         ` Gregory CLEMENT
2013-08-23 12:13         ` Sebastian Hesselbarth
2013-08-23 12:13           ` Sebastian Hesselbarth
2013-08-23 14:23           ` Gregory CLEMENT
2013-08-23 14:23             ` Gregory CLEMENT
2013-08-23 14:34             ` Gregory CLEMENT
2013-08-23 14:34               ` Gregory CLEMENT
2013-08-20  2:04 ` [RFC 09/17] ARM: mxs: " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 10/17] ARM: nspire: " Sebastian Hesselbarth
2013-08-20  2:04   ` Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 11/17] ARM: rockchip: " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 12/17] ARM: socfpga: " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 13/17] ARM: sti: " Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 14/17] ARM: tegra: remove .init_time hook to clocksource_of_init Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 15/17] ARM: vexpress: remove custom .init_time hook Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 16/17] clk: vt8500: remove call to of_clk_init Sebastian Hesselbarth
2013-08-20  2:04 ` [RFC 17/17] clk: zynq: " Sebastian Hesselbarth
2013-08-23  0:26   ` Sören Brinkmann
2013-08-23  0:26     ` Sören Brinkmann
2013-08-23  0:59     ` Sören Brinkmann
2013-08-23  0:59       ` Sören Brinkmann
2013-08-23  7:32       ` Steffen Trumtrar
2013-08-23  7:32         ` Steffen Trumtrar
2013-08-23 16:00         ` Sören Brinkmann
2013-08-23 16:00           ` Sören Brinkmann
2013-08-23 23:38           ` Steffen Trumtrar
2013-08-23 23:38             ` Steffen Trumtrar
2013-08-26 11:15         ` Michal Simek
2013-08-26 11:15           ` Michal Simek
2013-08-26 12:07           ` Steffen Trumtrar
2013-08-26 12:07             ` Steffen Trumtrar
2013-08-26 12:53             ` Sebastian Hesselbarth
2013-08-26 12:53               ` Sebastian Hesselbarth
2013-08-26 15:14               ` Michal Simek
2013-08-26 15:14                 ` Michal Simek
2013-08-26 15:31                 ` Steffen Trumtrar
2013-08-26 15:31                   ` Steffen Trumtrar
2013-08-26 15:16               ` Sören Brinkmann
2013-08-26 15:16                 ` Sören Brinkmann
2013-08-26 15:33                 ` Steffen Trumtrar
2013-08-26 15:33                   ` Steffen Trumtrar
2013-08-23  9:30       ` Sebastian Hesselbarth
2013-08-23  9:30         ` Sebastian Hesselbarth
2013-08-23 17:19         ` Sören Brinkmann
2013-08-23 17:19           ` Sören Brinkmann
2013-08-23 17:44           ` Sebastian Hesselbarth
2013-08-23 17:44             ` Sebastian Hesselbarth
2013-08-23 23:22             ` Steffen Trumtrar
2013-08-23 23:22               ` Steffen Trumtrar
2013-08-26 15:20             ` Sören Brinkmann
2013-08-26 15:20               ` Sören Brinkmann
2013-08-27 21:27 ` [PATCH RFC v2 00/16] ARM: provide common arch init for DT clocks Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
     [not found] ` <1376964271-22715-1-git-send-email-sebastian.hesselbarth-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-08-27 21:27   ` [PATCH RFC v2 01/16] ARM: call clk_of_init from time_init Sebastian Hesselbarth
2013-08-27 21:27     ` Sebastian Hesselbarth
2013-08-27 21:27     ` Sebastian Hesselbarth
2013-08-27 22:19     ` Sören Brinkmann
2013-08-27 22:19       ` Sören Brinkmann
2013-08-27 22:19       ` Sören Brinkmann
2013-08-27 22:58       ` Sebastian Hesselbarth
2013-08-27 22:58         ` Sebastian Hesselbarth
2013-08-27 23:20         ` Sören Brinkmann
2013-08-27 23:20           ` Sören Brinkmann
2013-08-27 23:20           ` Sören Brinkmann
2013-08-29 13:45         ` Arnd Bergmann
2013-08-29 13:45           ` Arnd Bergmann
2013-09-04 19:32           ` Sebastian Hesselbarth
2013-09-04 19:32             ` Sebastian Hesselbarth
2013-09-04 20:41             ` Sören Brinkmann
2013-09-04 20:41               ` Sören Brinkmann
2013-09-04 20:52               ` Sebastian Hesselbarth
2013-09-04 20:52                 ` Sebastian Hesselbarth
2013-09-04 20:59                 ` Sören Brinkmann
2013-09-04 20:59                   ` Sören Brinkmann
2013-09-05  9:34                   ` Arnd Bergmann
2013-09-05  9:34                     ` Arnd Bergmann
2013-08-27 21:27 ` [PATCH RFC v2 02/16] ARM: dove: remove custom .init_time hook Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
2013-08-27 21:27 ` [PATCH RFC v2 03/16] ARM: exynos: " Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
2013-08-27 21:27 ` [PATCH RFC v2 04/16] ARM: highbank: " Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
2013-08-27 23:13   ` Mike Turquette
2013-08-27 23:13     ` Mike Turquette
2013-08-27 21:27 ` [PATCH RFC v2 05/16] ARM: imx: " Sebastian Hesselbarth
2013-08-27 21:27   ` Sebastian Hesselbarth
2013-08-29 11:00   ` Shawn Guo
2013-08-29 11:00     ` Shawn Guo
2013-08-27 21:28 ` [PATCH RFC v2 06/16] ARM: kirkwood: " Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-27 21:28 ` [PATCH RFC v2 07/16] ARM: mvebu: " Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-28  6:28   ` Gregory CLEMENT
2013-08-28  6:28     ` Gregory CLEMENT
2013-08-27 21:28 ` [PATCH RFC v2 08/16] ARM: mxs: " Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-27 23:16   ` Mike Turquette
2013-08-27 23:16     ` Mike Turquette
2013-08-29 11:08   ` Shawn Guo
2013-08-29 11:08     ` Shawn Guo
2013-08-29 11:32     ` Sebastian Hesselbarth
2013-08-29 11:32       ` Sebastian Hesselbarth
2013-08-29 12:58       ` Shawn Guo
2013-08-29 12:58         ` Shawn Guo
2013-08-27 21:28 ` [PATCH RFC v2 09/16] ARM: nspire: " Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-27 21:28 ` [PATCH RFC v2 10/16] ARM: rockchip: " Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-27 21:28 ` [PATCH RFC v2 11/16] ARM: socfpga: remove call to of_clk_init Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-29 15:38   ` Dinh Nguyen
2013-08-29 15:38     ` Dinh Nguyen
2013-08-29 17:23     ` Arnd Bergmann
2013-08-29 17:23       ` Arnd Bergmann
2013-08-27 21:28 ` [PATCH RFC v2 12/16] ARM: sti: remove custom .init_time hook Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-29 16:29   ` [STLinux Kernel] " Srinivas KANDAGATLA
2013-08-29 16:29     ` Srinivas KANDAGATLA
2013-08-27 21:28 ` [PATCH RFC v2 13/16] ARM: tegra: split tegra_pmc_init() in two Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
     [not found]   ` <1377638890-371-14-git-send-email-sebastian.hesselbarth-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-08-27 21:59     ` Stephen Warren
2013-08-27 21:59       ` Stephen Warren
2013-08-27 21:59       ` Stephen Warren
     [not found]       ` <521D214C.80809-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-08-27 22:09         ` Sebastian Hesselbarth
2013-08-27 22:09           ` Sebastian Hesselbarth
2013-08-27 22:09           ` Sebastian Hesselbarth
2013-09-11 19:56     ` Stephen Warren
2013-09-11 19:56       ` Stephen Warren
2013-09-11 19:56       ` Stephen Warren
     [not found]       ` <5230CAF7.6010103-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-09-12  6:21         ` Sebastian Hesselbarth
2013-09-12  6:21           ` Sebastian Hesselbarth
2013-09-12  6:21           ` Sebastian Hesselbarth
2013-09-12 16:32           ` Stephen Warren
2013-09-12 16:32             ` Stephen Warren
2013-08-27 21:28 ` [PATCH RFC v2 14/16] ARM: vexpress: remove custom .init_time hook Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-29 13:35   ` Arnd Bergmann
2013-08-29 13:35     ` Arnd Bergmann
2013-08-29 18:16     ` Sebastian Hesselbarth
2013-08-29 18:16       ` Sebastian Hesselbarth
2013-08-30 10:02       ` Jon Medhurst (Tixy)
2013-08-30 10:02         ` Jon Medhurst (Tixy)
2013-08-30 11:39         ` Russell King - ARM Linux
2013-08-30 11:39           ` Russell King - ARM Linux
2013-08-30 13:12         ` Pawel Moll
2013-08-30 13:12           ` Pawel Moll
2013-08-27 21:28 ` [PATCH RFC v2 15/16] clk: vt8500: remove call to of_clk_init Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-27 23:16   ` Mike Turquette
2013-08-27 23:16     ` Mike Turquette
2013-08-29 13:42   ` Arnd Bergmann
2013-08-29 13:42     ` Arnd Bergmann
2013-08-27 21:28 ` [PATCH RFC v2 16/16] ARM: zynq: Don't call of_clk_init() Sebastian Hesselbarth
2013-08-27 21:28   ` Sebastian Hesselbarth
2013-08-29 13:37   ` Arnd Bergmann
2013-08-29 13:37     ` Arnd Bergmann
2013-08-29 14:21     ` Michal Simek
2013-08-29 14:21       ` Michal Simek
2013-08-29 17:20       ` Arnd Bergmann
2013-08-29 17:20         ` Arnd Bergmann
2013-08-29 18:14         ` Michal Simek
2013-08-29 18:14           ` Michal Simek
2013-08-29 18:20     ` Sebastian Hesselbarth
2013-08-29 18:20       ` Sebastian Hesselbarth

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