From: thomas.petazzoni@free-electrons.com (Thomas Petazzoni)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 5/5] arm: dts: Convert mvebu device tree files to 64 bits
Date: Thu, 21 Mar 2013 22:16:13 +0100 [thread overview]
Message-ID: <20130321221613.53a48845@skate> (raw)
In-Reply-To: <20130321203751.GP21478@lunn.ch>
Dear Andrew Lunn,
On Thu, 21 Mar 2013 21:37:51 +0100, Andrew Lunn wrote:
> > And I'm not sure the SDRAM address decoding windows allows to split the
> > first 4 GB of RAM into two areas, one that would be mapped starting at
> > physical address 0x0, and another area that would be mapped at a
> > different address (above 4 GB).
>
> So why not map the whole SDRAM above 4GB physical address?
As Lior rightly pointed out to me, this would prevent any device from
DMA-ing to or from the RAM. Devices can only access the first 32 bits
of the physical address space. So there must be some RAM below 4 GB.
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>,
Jason Cooper <jason@lakedaemon.net>,
Grant Likely <grant.likely@secretlab.ca>,
Rob Herring <rob.herring@calxeda.com>,
Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
linux-arm-kernel@lists.infradead.org,
devicetree-discuss@lists.ozlabs.org,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Olof Johansson <olof@lixom.net>, Nicolas Pitre <nico@fluxnic.net>,
Lior Amsalem <alior@marvell.com>,
Maen Suleiman <maen@marvell.com>,
Tawfik Bayouk <tawfik@marvell.com>,
Shadi Ammouri <shadi@marvell.com>,
Eran Ben-Avi <benavi@marvell.com>,
Yehuda Yitschak <yehuday@marvell.com>,
Nadav Haklai <nadavh@marvell.com>,
Ike Pan <ike.pan@canonical.com>,
Chris Van Hoof <vanhoof@canonical.com>,
Dan Frazier <dann.frazier@canonical.com>,
Leif Lindholm <leif.lindholm@arm.com>,
Jon Masters <jcm@redhat.com>
Subject: Re: [PATCH 5/5] arm: dts: Convert mvebu device tree files to 64 bits
Date: Thu, 21 Mar 2013 22:16:13 +0100 [thread overview]
Message-ID: <20130321221613.53a48845@skate> (raw)
In-Reply-To: <20130321203751.GP21478@lunn.ch>
Dear Andrew Lunn,
On Thu, 21 Mar 2013 21:37:51 +0100, Andrew Lunn wrote:
> > And I'm not sure the SDRAM address decoding windows allows to split the
> > first 4 GB of RAM into two areas, one that would be mapped starting at
> > physical address 0x0, and another area that would be mapped at a
> > different address (above 4 GB).
>
> So why not map the whole SDRAM above 4GB physical address?
As Lior rightly pointed out to me, this would prevent any device from
DMA-ing to or from the RAM. Devices can only access the first 32 bits
of the physical address space. So there must be some RAM below 4 GB.
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>,
Jason Cooper <jason@lakedaemon.net>,
Grant Likely <grant.likely@secretlab.ca>,
Rob Herring <rob.herring@calxeda.com>,
Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
linux-arm-kernel@lists.infradead.org,
devicetree-discuss@lists.ozlabs.org,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Olof Johansson <olof@lixom.net>, Nicolas Pitre <nico@fluxnic.net>,
Lior Amsalem <alior@marvell.com>,
Maen Suleiman <maen@marvell.com>,
Tawfik Bayouk <tawfik@marvell.com>,
Shadi Ammouri <shadi@marvell.com>,
Eran Ben-Avi <benavi@marvell.com>,
Yehuda Yitschak <yehuday@marvell.com>,
Nadav Haklai <nadavh@marvell.com>,
Ike Pan <ike.pan@canonical.com>,
Chris Van Hoof <vanhoof@canonical.com>,
Dan Frazier <dann.frazier@canonical.com>,
Leif Lindholm <leif.lindholm@arm.com>,
Jon Masters <jcm@redhat.com>, David Marlin <dmarlin@redhat.com>,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH 5/5] arm: dts: Convert mvebu device tree files to 64 bits
Date: Thu, 21 Mar 2013 22:16:13 +0100 [thread overview]
Message-ID: <20130321221613.53a48845@skate> (raw)
In-Reply-To: <20130321203751.GP21478@lunn.ch>
Dear Andrew Lunn,
On Thu, 21 Mar 2013 21:37:51 +0100, Andrew Lunn wrote:
> > And I'm not sure the SDRAM address decoding windows allows to split the
> > first 4 GB of RAM into two areas, one that would be mapped starting at
> > physical address 0x0, and another area that would be mapped at a
> > different address (above 4 GB).
>
> So why not map the whole SDRAM above 4GB physical address?
As Lior rightly pointed out to me, this would prevent any device from
DMA-ing to or from the RAM. Devices can only access the first 32 bits
of the physical address space. So there must be some RAM below 4 GB.
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
next prev parent reply other threads:[~2013-03-21 21:16 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 16:26 [PATCH 0/5] arm: mvebu: Enable LPAE support for Armada XP SoCs Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 1/5] arm: mvebu: Aligne the internal registers virtual base to support LPAE Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 2/5] arm: mvebu: Select DMA_BOUNCE when LPAE is selected in Kconfig Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 18:19 ` Rob Herring
2013-03-21 18:19 ` Rob Herring
2013-03-21 19:18 ` Andrew Lunn
2013-03-21 19:18 ` Andrew Lunn
2013-03-21 19:18 ` Andrew Lunn
2013-03-22 11:32 ` Russell King - ARM Linux
2013-03-22 11:32 ` Russell King - ARM Linux
2013-03-22 11:32 ` Russell King - ARM Linux
[not found] ` <20130322113251.GB4977-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2013-03-23 19:48 ` Krzysztof Halasa
2013-03-21 16:26 ` [PATCH 3/5] arm: mvebu: Enable pj4b on LPAE compilations Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 4/5] arm: dts: Add a 64 bits version of the skeleton device tree Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 5/5] arm: dts: Convert mvebu device tree files to 64 bits Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 16:26 ` Gregory CLEMENT
2013-03-21 17:59 ` Rob Herring
2013-03-21 17:59 ` Rob Herring
2013-03-21 17:59 ` Rob Herring
2013-03-21 19:03 ` Arnd Bergmann
2013-03-21 19:03 ` Arnd Bergmann
2013-03-21 19:03 ` Arnd Bergmann
2013-03-21 19:18 ` Thomas Petazzoni
2013-03-21 19:18 ` Thomas Petazzoni
2013-03-21 19:18 ` Thomas Petazzoni
2013-03-21 21:31 ` Arnd Bergmann
2013-03-21 21:31 ` Arnd Bergmann
2013-03-21 21:31 ` Arnd Bergmann
2013-03-21 22:30 ` Sebastian Hesselbarth
2013-03-21 22:30 ` Sebastian Hesselbarth
2013-03-21 22:30 ` Sebastian Hesselbarth
2013-03-21 20:15 ` Andrew Lunn
2013-03-21 20:15 ` Andrew Lunn
2013-03-21 20:15 ` Andrew Lunn
2013-03-21 20:22 ` Thomas Petazzoni
2013-03-21 20:22 ` Thomas Petazzoni
2013-03-21 20:22 ` Thomas Petazzoni
2013-03-21 20:30 ` Jason Cooper
2013-03-21 20:30 ` Jason Cooper
2013-03-21 20:30 ` Jason Cooper
2013-03-21 20:37 ` Andrew Lunn
2013-03-21 20:37 ` Andrew Lunn
2013-03-21 20:37 ` Andrew Lunn
2013-03-21 21:08 ` Thomas Petazzoni
2013-03-21 21:08 ` Thomas Petazzoni
2013-03-21 21:08 ` Thomas Petazzoni
2013-03-21 21:16 ` Thomas Petazzoni [this message]
2013-03-21 21:16 ` Thomas Petazzoni
2013-03-21 21:16 ` Thomas Petazzoni
2013-03-21 20:55 ` Jason Gunthorpe
2013-03-21 20:55 ` Jason Gunthorpe
2013-03-21 20:55 ` Jason Gunthorpe
2013-03-21 21:15 ` Thomas Petazzoni
2013-03-21 21:15 ` Thomas Petazzoni
2013-03-21 21:15 ` Thomas Petazzoni
2013-03-21 21:35 ` Lior Amsalem
2013-03-21 21:35 ` Lior Amsalem
2013-03-21 21:46 ` Jason Gunthorpe
2013-03-21 21:46 ` Jason Gunthorpe
2013-03-21 21:58 ` Lior Amsalem
2013-03-21 21:58 ` Lior Amsalem
2013-03-22 6:55 ` Arnd Bergmann
2013-03-22 6:55 ` Arnd Bergmann
2013-03-21 21:41 ` Jason Gunthorpe
2013-03-21 21:41 ` Jason Gunthorpe
2013-03-21 21:41 ` Jason Gunthorpe
2013-03-21 22:26 ` Sebastian Hesselbarth
2013-03-21 22:26 ` Sebastian Hesselbarth
2013-03-21 22:26 ` Sebastian Hesselbarth
2013-03-22 9:55 ` Arnd Bergmann
2013-03-22 9:55 ` Arnd Bergmann
2013-03-21 21:25 ` Andrew Lunn
2013-03-21 21:25 ` Andrew Lunn
2013-03-22 6:28 ` Andrew Lunn
2013-03-22 6:28 ` Andrew Lunn
2013-03-22 17:43 ` Jason Gunthorpe
2013-03-22 17:43 ` Jason Gunthorpe
2013-03-22 19:33 ` Arnd Bergmann
2013-03-22 19:33 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130321221613.53a48845@skate \
--to=thomas.petazzoni@free-electrons.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.