From: Thierry Reding <thierry.reding@avionic-design.de>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-tegra@vger.kernel.org,
Grant Likely <grant.likely@secretlab.ca>,
Rob Herring <rob.herring@calxeda.com>,
Russell King <linux@arm.linux.org.uk>,
Stephen Warren <swarren@wwwdotorg.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Andrew Murray <andrew.murray@arm.com>,
Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
devicetree-discuss@lists.ozlabs.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH 05/14] lib: Add I/O map cache implementation
Date: Wed, 9 Jan 2013 22:54:28 +0100 [thread overview]
Message-ID: <20130109215428.GA13648@avionic-0098.adnet.avionic-design.de> (raw)
In-Reply-To: <201301092119.57067.arnd@arndb.de>
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On Wed, Jan 09, 2013 at 09:19:56PM +0000, Arnd Bergmann wrote:
> On Wednesday 09 January 2013, Thierry Reding wrote:
> > The I/O map cache is used to map large regions of physical memory in
> > smaller chunks to avoid running out of vmalloc()/ioremap() space.
> >
> > Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
>
> Can you explain why this is necessary and which problem it solves?
> The implementation looks reasonable, but it's not clear to me if
> we really need this new interface.
>
> In what cases does it actually save ioremap space?
I briefly described this in the cover letter of this series and didn't
realize I hadn't put more information in this patch's commit message.
What happens on Tegra is that we need to map 256 MiB of physical memory
to access all the PCIe extended configuration space. However, ioremap()
on such a large region fails if not enough vmalloc() space is available.
This was observed when somebody tested this on CardHu which has a 1 GiB
of RAM and therefore remapping the full 256 MiB fails.
Thierry
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next prev parent reply other threads:[~2013-01-09 21:54 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-09 20:43 [PATCH 00/14] Rewrite Tegra PCIe driver Thierry Reding
2013-01-09 20:43 ` [PATCH 01/14] of/pci: Provide support for parsing PCI DT ranges property Thierry Reding
2013-01-11 0:06 ` Stephen Warren
2013-01-11 4:02 ` Thierry Reding
2013-01-09 20:43 ` [PATCH 02/14] of/pci: Add of_pci_get_devfn() function Thierry Reding
2013-01-11 0:09 ` Stephen Warren
2013-01-11 4:06 ` Thierry Reding
2013-01-09 20:43 ` [PATCH 03/14] of/pci: Add of_pci_get_bus() function Thierry Reding
2013-01-09 20:43 ` [PATCH 04/14] of/pci: Add of_pci_parse_bus_range() function Thierry Reding
2013-01-09 20:43 ` [PATCH 05/14] lib: Add I/O map cache implementation Thierry Reding
2013-01-09 21:19 ` Arnd Bergmann
2013-01-09 21:54 ` Thierry Reding [this message]
2013-01-09 22:10 ` Arnd Bergmann
2013-01-09 23:12 ` Stephen Warren
2013-01-09 23:17 ` Jason Gunthorpe
2013-01-10 7:19 ` Thierry Reding
2013-01-10 9:17 ` Arnd Bergmann
2013-01-10 10:25 ` Thierry Reding
2013-01-10 18:20 ` Jason Gunthorpe
2013-01-10 18:55 ` Thierry Reding
2013-01-10 19:03 ` Thierry Reding
2013-01-10 19:24 ` Jason Gunthorpe
2013-01-10 20:20 ` Thierry Reding
2013-01-10 21:06 ` Jason Gunthorpe
2013-01-16 10:18 ` Thierry Reding
2013-01-16 11:25 ` Russell King - ARM Linux
2013-01-16 11:52 ` Thierry Reding
2013-01-10 18:26 ` Arnd Bergmann
2013-01-10 18:57 ` Thierry Reding
2013-01-10 7:10 ` Thierry Reding
2013-01-09 21:28 ` Russell King - ARM Linux
2013-01-09 21:57 ` Thierry Reding
2013-01-09 20:43 ` [PATCH 06/14] ARM: pci: Keep pci_common_init() around after init Thierry Reding
2013-02-05 20:41 ` Thierry Reding
2013-02-06 16:30 ` Russell King - ARM Linux
2013-02-06 19:35 ` Thierry Reding
2013-02-06 8:36 ` Thomas Petazzoni
2013-02-06 16:38 ` Linus Walleij
2013-02-07 0:54 ` Arnd Bergmann
2013-02-06 17:07 ` Linus Walleij
2013-02-07 1:20 ` Arnd Bergmann
2013-01-09 20:43 ` [PATCH 07/14] ARM: pci: Allow passing per-controller private data Thierry Reding
2013-01-09 20:43 ` [PATCH 08/14] ARM: tegra: Move tegra_pcie_xclk_clamp() to PMC Thierry Reding
2013-01-09 20:43 ` [PATCH 09/14] ARM: tegra: Move pmc.h to include/mach Thierry Reding
2013-01-11 0:15 ` Stephen Warren
2013-01-11 4:08 ` Thierry Reding
2013-01-09 20:43 ` [PATCH 10/14] PCI: tegra: Move PCIe driver to drivers/pci/host Thierry Reding
2013-01-09 21:22 ` Arnd Bergmann
2013-01-09 21:58 ` Thierry Reding
2013-01-09 22:03 ` Arnd Bergmann
2013-01-10 23:54 ` Stephen Warren
2013-01-11 3:40 ` Thierry Reding
2013-01-11 15:36 ` Arnd Bergmann
2013-01-11 15:45 ` Thierry Reding
2013-01-12 12:36 ` Thierry Reding
2013-01-12 21:12 ` Arnd Bergmann
2013-01-13 9:58 ` Thierry Reding
2013-01-14 9:57 ` Andrew Murray
2013-01-15 12:08 ` Thierry Reding
2013-01-15 12:44 ` Arnd Bergmann
2013-01-15 15:40 ` Andrew Murray
2013-01-15 21:14 ` Thierry Reding
2013-01-16 14:00 ` Arnd Bergmann
2013-01-16 16:17 ` Andrew Murray
2013-01-16 18:31 ` Thierry Reding
2013-01-17 15:42 ` Andrew Murray
2013-01-17 16:05 ` Thierry Reding
2013-01-17 16:22 ` Andrew Murray
2013-01-17 20:30 ` Thierry Reding
2013-01-18 9:18 ` Andrew Murray
2013-01-22 19:29 ` Jason Gunthorpe
2013-01-29 13:31 ` Andrew Murray
2013-01-11 0:48 ` Stephen Warren
2013-01-11 3:52 ` Thierry Reding
2013-01-11 20:34 ` Stephen Warren
2013-01-18 9:56 ` Andrew Murray
2013-01-18 10:09 ` Thierry Reding
2013-02-13 23:11 ` Thomas Petazzoni
2013-01-09 20:43 ` [PATCH 11/14] ARM: tegra: tamonten: Add PCIe support Thierry Reding
2013-01-09 21:23 ` Arnd Bergmann
2013-01-10 20:21 ` Thierry Reding
2013-01-09 20:43 ` [PATCH 12/14] ARM: tegra: tec: " Thierry Reding
2013-01-11 0:22 ` Stephen Warren
2013-01-11 4:34 ` Thierry Reding
2013-01-09 20:43 ` [PATCH 13/14] ARM: tegra: harmony: Initialize PCIe from DT Thierry Reding
2013-01-10 23:58 ` Stephen Warren
2013-01-09 20:43 ` [PATCH 14/14] ARM: tegra: trimslice: " Thierry Reding
2013-01-10 23:56 ` Stephen Warren
2013-01-11 18:48 ` Thierry Reding
2013-01-09 21:25 ` [PATCH 00/14] Rewrite Tegra PCIe driver Thomas Petazzoni
2013-01-10 6:55 ` Thierry Reding
2013-01-10 8:34 ` Thomas Petazzoni
2013-01-28 18:15 ` Bjorn Helgaas
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