From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Cc: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-ide-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Oliver Schinagl <oliver-dxLnbx3+1qmEVqv0pETR8A@public.gmane.org>,
Richard Zhu
<Hong-Xing.Zhu-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org,
Maxime Ripard
<maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [RFC v3 08/13] ahci-platform: Allow specifying platform_data through of_device_id
Date: Sun, 19 Jan 2014 08:19:10 -0500 [thread overview]
Message-ID: <20140119131910.GF11123@htj.dyndns.org> (raw)
In-Reply-To: <20140119123055.GO15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
On Sun, Jan 19, 2014 at 12:30:55PM +0000, Russell King - ARM Linux wrote:
> I don't see anything wrong with this. Platform data should _never_ be
> written to, because doing so will change the driver behaviour between
> bindings. It really should be read-only to driver code.
Hmmm, problems usually arise when const is used to distinguish ro and
rw users. When it's simple, it seems okay but later on it often ends
up requiring dropping const in almost arbitrary places or forced casts
somewhere random. Over time, it makes const annotations in the kernel
sparse and inconsistent. For anything non-trivial, I think it's best
to ignore it.
That said, if the object is actually immutable once initialized, it
shouldn't cause any trouble. That probably is one of the few proper
use case for const on complex data types.
Thanks.
--
tejun
WARNING: multiple messages have this Message-ID (diff)
From: tj@kernel.org (Tejun Heo)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC v3 08/13] ahci-platform: Allow specifying platform_data through of_device_id
Date: Sun, 19 Jan 2014 08:19:10 -0500 [thread overview]
Message-ID: <20140119131910.GF11123@htj.dyndns.org> (raw)
In-Reply-To: <20140119123055.GO15937@n2100.arm.linux.org.uk>
On Sun, Jan 19, 2014 at 12:30:55PM +0000, Russell King - ARM Linux wrote:
> I don't see anything wrong with this. Platform data should _never_ be
> written to, because doing so will change the driver behaviour between
> bindings. It really should be read-only to driver code.
Hmmm, problems usually arise when const is used to distinguish ro and
rw users. When it's simple, it seems okay but later on it often ends
up requiring dropping const in almost arbitrary places or forced casts
somewhere random. Over time, it makes const annotations in the kernel
sparse and inconsistent. For anything non-trivial, I think it's best
to ignore it.
That said, if the object is actually immutable once initialized, it
shouldn't cause any trouble. That probably is one of the few proper
use case for const on complex data types.
Thanks.
--
tejun
next prev parent reply other threads:[~2014-01-19 13:19 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-18 23:48 [RFC v3 00/13] ahci: add sunxi driver and cleanup imx driver Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-1-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-18 23:48 ` [RFC v3 01/13] libahci: Allow drivers to override start_engine Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-2-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 4:46 ` Tejun Heo
2014-01-19 4:46 ` Tejun Heo
[not found] ` <20140119044643.GH3640-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-01-19 18:48 ` Hans de Goede
2014-01-19 18:48 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 02/13] sata-highbank: Remove unnecessary ahci_platform.h include Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-3-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 11:15 ` Tejun Heo
2014-01-19 11:15 ` Tejun Heo
2014-01-18 23:48 ` [RFC v3 03/13] ahci-platform: Fix clk enable/disable unbalance on suspend/resume Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-4-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 11:14 ` Tejun Heo
2014-01-19 11:14 ` Tejun Heo
[not found] ` <20140119111412.GA11123-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-01-19 18:47 ` Hans de Goede
2014-01-19 18:47 ` Hans de Goede
[not found] ` <52DC1DAA.3010403-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 19:15 ` Tejun Heo
2014-01-19 19:15 ` Tejun Heo
[not found] ` <20140119191554.GB32165-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-01-19 19:52 ` Hans de Goede
2014-01-19 19:52 ` Hans de Goede
[not found] ` <52DC2CF5.5080109-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-20 12:26 ` Tejun Heo
2014-01-20 12:26 ` Tejun Heo
2014-01-18 23:48 ` [RFC v3 04/13] ahci-platform: Undo pdata->resume on resume failure Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-5-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 11:27 ` Tejun Heo
2014-01-19 11:27 ` Tejun Heo
[not found] ` <20140119112737.GC11123-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-01-19 18:40 ` Hans de Goede
2014-01-19 18:40 ` Hans de Goede
[not found] ` <52DC1C15.1030107-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 19:13 ` Tejun Heo
2014-01-19 19:13 ` Tejun Heo
[not found] ` <20140119191349.GA32165-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-01-19 19:34 ` Hans de Goede
2014-01-19 19:34 ` Hans de Goede
[not found] ` <52DC28DB.7070804-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 19:42 ` Tejun Heo
2014-01-19 19:42 ` Tejun Heo
[not found] ` <20140119194226.GE32165-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-01-19 19:53 ` Hans de Goede
2014-01-19 19:53 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 05/13] ahci-platform: Pass ahci_host_priv ptr to ahci_platform_data init method Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-6-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 11:30 ` Tejun Heo
2014-01-19 11:30 ` Tejun Heo
[not found] ` <20140119113051.GD11123-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-01-19 18:51 ` Hans de Goede
2014-01-19 18:51 ` Hans de Goede
[not found] ` <52DC1EC4.3090807-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 19:17 ` Tejun Heo
2014-01-19 19:17 ` Tejun Heo
[not found] ` <20140119191706.GC32165-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-01-19 19:56 ` Hans de Goede
2014-01-19 19:56 ` Hans de Goede
[not found] ` <52DC2DD9.7070403-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-20 12:28 ` Tejun Heo
2014-01-20 12:28 ` Tejun Heo
2014-01-18 23:48 ` [RFC v3 06/13] ahci-platform: Add support for devices with more then 1 clock Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-7-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 12:38 ` Russell King - ARM Linux
2014-01-19 12:38 ` Russell King - ARM Linux
[not found] ` <20140119123854.GP15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 19:20 ` Hans de Goede
2014-01-19 19:20 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 07/13] ahci-platform: Add support for an optional regulator for sata-target power Hans de Goede
2014-01-18 23:48 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 08/13] ahci-platform: Allow specifying platform_data through of_device_id Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-9-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 11:38 ` Tejun Heo
2014-01-19 11:38 ` Tejun Heo
2014-01-19 12:30 ` Russell King - ARM Linux
2014-01-19 12:30 ` Russell King - ARM Linux
[not found] ` <20140119123055.GO15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 13:19 ` Tejun Heo [this message]
2014-01-19 13:19 ` Tejun Heo
[not found] ` <20140119113838.GE11123-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-01-19 18:56 ` Hans de Goede
2014-01-19 18:56 ` Hans de Goede
[not found] ` <52DC1FF5.80101-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 19:22 ` Tejun Heo
2014-01-19 19:22 ` Tejun Heo
2014-01-20 8:24 ` Sascha Hauer
2014-01-20 8:24 ` Sascha Hauer
[not found] ` <20140120082438.GH16215-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2014-01-20 8:35 ` Hans de Goede
2014-01-20 8:35 ` Hans de Goede
2014-01-20 9:09 ` Sascha Hauer
2014-01-20 9:09 ` Sascha Hauer
[not found] ` <20140120090950.GI16215-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2014-01-20 9:17 ` Hans de Goede
2014-01-20 9:17 ` Hans de Goede
2014-01-20 9:57 ` Sascha Hauer
2014-01-20 9:57 ` Sascha Hauer
2014-01-18 23:48 ` [RFC v3 09/13] ARM: sunxi: Add support for Allwinner SUNXi SoCs sata to ahci_platform Hans de Goede
2014-01-18 23:48 ` Hans de Goede
2014-01-19 12:22 ` Russell King - ARM Linux
2014-01-19 12:22 ` Russell King - ARM Linux
[not found] ` <20140119122216.GM15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 19:07 ` Hans de Goede
2014-01-19 19:07 ` Hans de Goede
2014-01-19 19:56 ` Russell King - ARM Linux
2014-01-19 19:56 ` Russell King - ARM Linux
[not found] ` <20140119195642.GU15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 20:01 ` Hans de Goede
2014-01-19 20:01 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 10/13] ahci_imx: Adjust for ahci_platform managing the clocks Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-11-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 12:41 ` Russell King - ARM Linux
2014-01-19 12:41 ` Russell King - ARM Linux
[not found] ` <20140119124134.GQ15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 19:30 ` Hans de Goede
2014-01-19 19:30 ` Hans de Goede
[not found] ` <52DC27DD.5030309-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 19:32 ` Russell King - ARM Linux
2014-01-19 19:32 ` Russell King - ARM Linux
[not found] ` <20140119193258.GT15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 19:38 ` Hans de Goede
2014-01-19 19:38 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 11/13] ahci-imx: Don't create a nested platform device from probe Hans de Goede
2014-01-18 23:48 ` Hans de Goede
[not found] ` <1390088935-7193-12-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-01-19 12:25 ` Russell King - ARM Linux
2014-01-19 12:25 ` Russell King - ARM Linux
[not found] ` <20140119122540.GN15937-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2014-01-19 19:08 ` Hans de Goede
2014-01-19 19:08 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 12/13] ARM: sun4i: dts: Add ahci / sata support Hans de Goede
2014-01-18 23:48 ` Hans de Goede
2014-01-18 23:48 ` [RFC v3 13/13] ARM: sun7i: " Hans de Goede
2014-01-18 23:48 ` Hans de Goede
2014-01-19 9:52 ` [RFC v3 00/13] ahci: add sunxi driver and cleanup imx driver Russell King - ARM Linux
2014-01-19 9:52 ` Russell King - ARM Linux
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