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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Andrzej Hajda <a.hajda@samsung.com>
Cc: "Tomeu Vizoso" <tomeu.vizoso@collabora.com>,
	linux-arm-kernel@lists.infradead.org,
	"Alexander Holler" <holler@ahsoftware.de>,
	"Alexandre Courbot" <gnurou@gmail.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Dmitry Torokhov" <dmitry.torokhov@gmail.com>,
	"Grant Likely" <grant.likely@linaro.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Ian Campbell" <ijc+devicetree@hellion.org.uk>,
	"Javier Martinez Canillas" <javier.martinez@collabora.co.uk>,
	"Krzysztof Kozlowski" <k.kozlowski@samsung.com>,
	"Kumar Gala" <galak@codeaurora.org>,
	"Len Brown" <lenb@kernel.org>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	linux-kernel@vger.kernel.org, "Lv Zheng" <lv.zheng@intel.com>,
	"Mark Brown" <broonie@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Pawel Moll" <pawel.moll@arm.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Robert Moore" <robert.moore@intel.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Stephen Warren" <swarren@wwwdotorg.org>,
	"Terje Bergström" <tbergstrom@nvidia.com>,
	"Thierry Reding" <thierry.reding@gmail.com>
Subject: Re: [PATCH 00/13] Discover and probe dependencies
Date: Thu, 18 Jun 2015 10:57:54 +0100	[thread overview]
Message-ID: <20150618095754.GI7557@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <55829269.2090309@samsung.com>

On Thu, Jun 18, 2015 at 11:42:01AM +0200, Andrzej Hajda wrote:
> 2. Provider create/register their resources only during probe.
>     It is not always the case - for example componentized drivers in
> probe often
>     calls only component_add, the real initialization is performed in
> bind callback.

bind is called in _a_ probe callback, but it may not be the probe callback
associated with the device.  (It'll be the final component's callback.)

I'm willing to be less critical of componentised drivers claiming their
resources in ->probe _iff_ they separate their data structures, like:

	struct foo_priv {
		void *base;
		struct clk *clk;
		struct dma_chan *chan;
		... other resource data ...;
		struct foo_runtime {
			... runtime data ...
		} rt;
	};

and then, in their bind callback, they memset the foo_runtime structure
to zero, to ensure that the driver always re-binds in the same state as
the first bind.

I've seen too many lax drivers over the years that this is a point I'm
very insistant on: either componentised drivers don't do any resource
claiming in their probe function, or they take steps to ensure non-
resource struct members are properly separated such that they can
guarantee that they aren't going to accidentally use something from a
previous binding.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 00/13] Discover and probe dependencies
Date: Thu, 18 Jun 2015 10:57:54 +0100	[thread overview]
Message-ID: <20150618095754.GI7557@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <55829269.2090309@samsung.com>

On Thu, Jun 18, 2015 at 11:42:01AM +0200, Andrzej Hajda wrote:
> 2. Provider create/register their resources only during probe.
>     It is not always the case - for example componentized drivers in
> probe often
>     calls only component_add, the real initialization is performed in
> bind callback.

bind is called in _a_ probe callback, but it may not be the probe callback
associated with the device.  (It'll be the final component's callback.)

I'm willing to be less critical of componentised drivers claiming their
resources in ->probe _iff_ they separate their data structures, like:

	struct foo_priv {
		void *base;
		struct clk *clk;
		struct dma_chan *chan;
		... other resource data ...;
		struct foo_runtime {
			... runtime data ...
		} rt;
	};

and then, in their bind callback, they memset the foo_runtime structure
to zero, to ensure that the driver always re-binds in the same state as
the first bind.

I've seen too many lax drivers over the years that this is a point I'm
very insistant on: either componentised drivers don't do any resource
claiming in their probe function, or they take steps to ensure non-
resource struct members are properly separated such that they can
guarantee that they aren't going to accidentally use something from a
previous binding.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

  reply	other threads:[~2015-06-18  9:58 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-17 13:42 [PATCH 00/13] Discover and probe dependencies Tomeu Vizoso
2015-06-17 13:42 ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 01/13] gpiolib: Fix docs for gpiochip_add_pingroup_range Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-07-13 12:16   ` Linus Walleij
2015-07-13 12:16     ` Linus Walleij
2015-06-17 13:42 ` [PATCH 02/13] driver-core: defer all probes until late_initcall Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-18 21:50   ` Rafael J. Wysocki
2015-06-18 21:50     ` Rafael J. Wysocki
2015-06-19 13:36     ` Tomeu Vizoso
2015-06-19 13:36       ` Tomeu Vizoso
2015-06-19 23:20       ` Rafael J. Wysocki
2015-06-19 23:20         ` Rafael J. Wysocki
2015-06-23  0:07         ` Rob Herring
2015-06-23  0:07           ` Rob Herring
2015-06-23 14:37           ` Rafael J. Wysocki
2015-06-23 14:37             ` Rafael J. Wysocki
2015-06-23 14:17             ` Tomeu Vizoso
2015-06-23 14:17               ` Tomeu Vizoso
2015-06-23 14:51               ` Rafael J. Wysocki
2015-06-23 14:51                 ` Rafael J. Wysocki
2015-06-23 14:37                 ` Tomeu Vizoso
2015-06-23 14:37                   ` Tomeu Vizoso
2015-06-24  0:14                   ` Rafael J. Wysocki
2015-06-24  0:14                     ` Rafael J. Wysocki
2015-06-17 13:42 ` [PATCH 03/13] ARM: tegra: Add gpio-ranges property Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 17:25   ` Mark Brown
2015-06-17 17:25     ` Mark Brown
2015-06-18  8:06     ` Tomeu Vizoso
2015-06-18  8:06       ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 04/13] pinctrl: tegra: Only set the gpio range if needed Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-07-13 20:14   ` Linus Walleij
2015-07-13 20:14     ` Linus Walleij
2015-07-14  8:34     ` Tomeu Vizoso
2015-07-14  8:34       ` Tomeu Vizoso
2015-07-15  3:17       ` Alexandre Courbot
2015-07-15  3:17         ` Alexandre Courbot
2015-07-15  8:13         ` Tomeu Vizoso
2015-07-15  8:13           ` Tomeu Vizoso
2015-07-17  8:04       ` Linus Walleij
2015-07-17  8:04         ` Linus Walleij
2015-07-17  8:19         ` Tomeu Vizoso
2015-07-17  8:19           ` Tomeu Vizoso
2015-07-17  9:36           ` Linus Walleij
2015-07-17  9:36             ` Linus Walleij
2015-06-17 13:42 ` [PATCH 05/13] driver core: fix docbook for device_private.device Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 06/13] of/platform: Set fwnode field for new devices Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 17:27   ` Mark Brown
2015-06-17 17:27     ` Mark Brown
2015-06-17 13:42 ` [PATCH 07/13] driver-core: Add class.get_dependencies() callback Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 08/13] gpio: sysfs: implement class.get_dependencies() Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 17:40   ` Mark Brown
2015-06-17 17:40     ` Mark Brown
2015-06-30 15:00     ` Tomeu Vizoso
2015-06-30 15:00       ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 09/13] gpu: host1x: " Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 10/13] driver-core: add for_each_class() Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 11/13] device property: add fwnode_get_parent() Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 12/13] device property: add fwnode_get_name() Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 13:42 ` [PATCH 13/13] driver-core: probe dependencies before probing Tomeu Vizoso
2015-06-17 13:42   ` Tomeu Vizoso
2015-06-17 18:13   ` Mark Brown
2015-06-17 18:13     ` Mark Brown
2015-06-30 15:18     ` Tomeu Vizoso
2015-06-30 15:18       ` Tomeu Vizoso
2015-06-18  9:42 ` [PATCH 00/13] Discover and probe dependencies Andrzej Hajda
2015-06-18  9:42   ` Andrzej Hajda
2015-06-18  9:57   ` Russell King - ARM Linux [this message]
2015-06-18  9:57     ` Russell King - ARM Linux
2015-06-18 10:36   ` Mark Brown
2015-06-18 10:36     ` Mark Brown
2015-06-18 13:14     ` Andrzej Hajda
2015-06-18 13:14       ` Andrzej Hajda
2015-06-18 14:38       ` Tomeu Vizoso
2015-06-18 14:38         ` Tomeu Vizoso
2015-06-18 14:49       ` Russell King - ARM Linux
2015-06-18 14:49         ` Russell King - ARM Linux
2015-06-18 15:32         ` Alexander Holler
2015-06-18 15:32           ` Alexander Holler
2015-06-18 14:57   ` Tomeu Vizoso
2015-06-18 14:57     ` Tomeu Vizoso

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