From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Bjorn Helgaas <helgaas@kernel.org>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Arnd Bergmann <arnd@arndb.de>, Will Deacon <will.deacon@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Richard Henderson <rth@twiddle.net>,
Tony Luck <tony.luck@intel.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Haavard Skinnemoen <hskinnemoen@gmail.com>,
Pratyush Anand <pratyush.anand@gmail.com>,
Jingoo Han <jingoohan1@gmail.com>,
Mingkai Hu <mingkai.hu@freescale.com>,
John Garry <john.garry@huawei.com>,
Tanmay Inamdar <tinamdar@apm.com>,
Murali Karicheri <m-karicheri2@ti.com>,
Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>,
Ray Jui <rjui@broadcom.com>, Wenrui Li <wenrui.li@rock-chips.com>,
Shawn Lin <shawn.lin@rock-chips.com>,
Minghuan Lian <minghuan.Lian@freescale.com>,
Jon Mason <jonmason@broadcom.com>,
Gabriele Paoloni <gabriele.paoloni@huawei.com>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
Joao Pinto <Joao.Pinto@synopsys.com>,
Thierry Reding <thierry.reding@gmail.com>,
Michal Simek <michal.simek@xilinx.com>,
Stanimir Varbanov <svarbanov@mm-sol.com>,
Zhou Wang <wangzhou1@hisilicon.com>,
Roy Zang <tie-fei.zang@freescale.com>
Subject: Re: [PATCH v2 02/22] asm-generic/io.h: add ioremap_nopost remap interface
Date: Thu, 6 Apr 2017 13:11:57 +0100 [thread overview]
Message-ID: <20170406121157.GD17774@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20170406105312.GE28800@wotan.suse.de>
On Thu, Apr 06, 2017 at 12:53:12PM +0200, Luis R. Rodriguez wrote:
> On Thu, Apr 06, 2017 at 11:26:36AM +0100, Lorenzo Pieralisi wrote:
> > Indeed, the static inline ioremap_nocache() fallback does not work
> > on all arches (whether I add the fallback in linux/io.h or
> > asm-generic/io.h is irrelevant), I bump into issues such as the one
> > reported above.
>
> Its also not *safe* to assume on behalf of all architectures a new ioremap
> call is both a good idea and proper.
You may be right in general, but not in this case.
Currently, many drivers use plain ioremap() to map this resource. We
are replacing that existing call - which is known to work in the majority
of cases - with a new call to cater for different semantics required by
an architecture.
Doing a replace of these ioremap() calls with ioremap_nopost() in this
situation, and then having ioremap_nopost() fail is a recipe for causing
lots and lots of regressions.
The only sane approach is to have ioremap_post() default to modelling the
_existing_ behaviour everywhere that it is used.
Requiring it to fail until architecture folk trip over the failure is
totally insane, and I very strongly disagree with you on this.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2017-04-06 12:11 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-27 9:49 [PATCH v2 00/22] PCI: fix config and I/O Address space memory mappings Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 01/22] PCI: remove __weak tag from pci_remap_iospace() Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 02/22] asm-generic/io.h: add ioremap_nopost remap interface Lorenzo Pieralisi
2017-03-28 1:41 ` Bjorn Helgaas
2017-03-28 14:45 ` Lorenzo Pieralisi
2017-03-30 16:47 ` Bjorn Helgaas
2017-04-05 10:58 ` Russell King - ARM Linux
2017-04-05 12:38 ` Lorenzo Pieralisi
2017-04-06 10:26 ` Lorenzo Pieralisi
2017-04-06 10:47 ` Russell King - ARM Linux
2017-04-10 14:30 ` Lorenzo Pieralisi
2017-04-06 10:53 ` Luis R. Rodriguez
2017-04-06 11:38 ` Lorenzo Pieralisi
2017-04-06 11:59 ` Luis R. Rodriguez
2017-04-06 13:07 ` Russell King - ARM Linux
2017-04-06 16:21 ` Lorenzo Pieralisi
2017-04-06 16:40 ` Russell King - ARM Linux
2017-04-06 17:09 ` Lorenzo Pieralisi
2017-04-06 17:19 ` Russell King - ARM Linux
2017-04-06 12:11 ` Russell King - ARM Linux [this message]
2017-04-06 12:25 ` Luis R. Rodriguez
2017-03-27 9:49 ` [PATCH v2 03/22] asm-generic/pgtable.h: introduce pgprot_nonposted remap attribute Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 04/22] PCI: fix pci_remap_iospace() " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 05/22] ARM64: implement ioremap_nopost() interface Lorenzo Pieralisi
2017-03-30 16:19 ` Will Deacon
2017-03-27 9:49 ` [PATCH v2 06/22] ARM: " Lorenzo Pieralisi
2017-03-31 11:08 ` Lorenzo Pieralisi
2017-04-05 10:21 ` Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 07/22] PCI: ECAM: use ioremap_nopost() to map config region Lorenzo Pieralisi
2017-03-30 16:20 ` Will Deacon
2017-03-27 9:49 ` [PATCH v2 08/22] lib: implement Devres ioremap_nopost() interface Lorenzo Pieralisi
2017-03-28 1:41 ` Bjorn Helgaas
2017-03-28 14:50 ` Lorenzo Pieralisi
2017-03-28 15:55 ` Tejun Heo
2017-03-27 9:49 ` [PATCH v2 09/22] PCI: xilinx: update PCI config space remap function Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 10/22] PCI: xilinx-nwl: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 11/22] PCI: spear13xx: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 12/22] PCI: rockchip: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 13/22] PCI: qcom: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 14/22] PCI: iproc-platform: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 15/22] PCI: hisi: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 16/22] PCI: designware: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 17/22] PCI: armada8k: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 18/22] PCI: xgene: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 19/22] PCI: tegra: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 20/22] PCI: layerscape: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 21/22] PCI: keystone-dw: " Lorenzo Pieralisi
2017-03-27 9:49 ` [PATCH v2 22/22] PCI: versatile: " Lorenzo Pieralisi
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