From: robherring2@gmail.com (Rob Herring)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: /proc/cpuinfo: Use DT machine name when possible
Date: Thu, 4 Dec 2014 12:10:30 -0600 [thread overview]
Message-ID: <CAL_JsqJ9i0jwaL1cyeomQG=bhhcnEgdGWYOqkcwidyk5xOUukg@mail.gmail.com> (raw)
In-Reply-To: <201412041857.49341@pali>
On Thu, Dec 4, 2014 at 11:57 AM, Pali Roh?r <pali.rohar@gmail.com> wrote:
> On Thursday 04 December 2014 17:49:40 Rob Herring wrote:
>> On Wed, Dec 3, 2014 at 6:48 PM, Pali Roh?r
> <pali.rohar@gmail.com> wrote:
>> > On Thursday 04 December 2014 01:33:08 Rob Herring wrote:
>> >> On Mon, Nov 24, 2014 at 4:19 PM, Pali Roh?r
>> >
>> > <pali.rohar@gmail.com> wrote:
>> >> > On Wednesday 18 June 2014 22:46:19 Rob Herring wrote:
>> >> >> On Wed, Jun 18, 2014 at 2:22 PM, Pali Roh?r
>> >> >
>> >> > <pali.rohar@gmail.com> wrote:
>> >> >> > On Wednesday 18 June 2014 21:07:35 Rob Herring wrote:
>> >> >> >> On Wed, Jun 18, 2014 at 11:54 AM, Pali Roh?r
>> >> >> >
>> >> >> > <pali.rohar@gmail.com> wrote:
>> >> >> >> > Machine name from board description is some generic
>> >> >> >> > name on DT kernel. DT provides machine name
>> >> >> >> > property which is specific for board, so use it
>> >> >> >> > instead generic one when possible.
>> >>
>> >> [...]
>> >>
>> >> >> > Basically in DT kernel is missing Hardware, Revision
>> >> >> > and probably also Serial key. (Now I used only qemu
>> >> >> > for testing which set serial key to 0). All these
>> >> >> > informations is used by userspace applications which
>> >> >> > determinate how to behave.
>> >> >>
>> >> >> It is somewhat fragile to expect the name in the DT to
>> >> >> match the old name from the kernel. As your patch to
>> >> >> n900 dts shows, we'd probably have to update every dts
>> >> >> file to make them match. While I think we should work
>> >> >> to remove this string from the kernel, userspace
>> >> >> depending on the DT model string is a bad idea. For
>> >> >> example, if you had some platform with multiple OEMs
>> >> >> just rebranding the same base design, they may all want
>> >> >> to put their own model string into each product. The
>> >> >> true h/w id is the compatible string.
>> >> >>
>> >> >> Serial number is easy. There is already a standard
>> >> >> although not widely used property for it with
>> >> >> "/serial-number". You just need to wire it up to
>> >> >> cpuinfo.
>> >> >
>> >> > There is no "/serial-number" property in kernel:
>> >> >
>> >> > $ ls -l -a /sys/bus/soc/devices/soc0/
>> >> > drwxr-xr-x 3 0 0 0 Jan 1 00:00
>> >> > . drwxr-xr-x 18 0 0 0 Jan 1
>> >> > 00:00 .. -r--r--r-- 1 0 0 4096 Jan
>> >> > 1 00:00 family -r--r--r-- 1 0 0
>> >> > 4096 Jan 1 00:00 machine drwxr-xr-x 2 0 0
>> >> > 0 Jan 1 00:00 power -r--r--r-- 1 0
>> >> > 0
>> >> > 4096 Jan 1 00:00 revision lrwxrwxrwx 1 0 0
>> >> >
>> >> > 0 Jan 1 00:00 subsystem -> ../../bus/soc
>> >> >
>> >> > -r--r--r-- 1 0 0 4096 Jan 1 00:00
>> >> > type -rw-r--r-- 1 0 0 4096 Jan 1
>> >> > 00:00 uevent
>> >>
>> >> Wrong place. If you put /serial-number in your DT, then it
>> >> will be in /proc/device-tree/serial-number.
>> >>
>> >> If you want to wire that up to /proc/cpuinfo, I would be
>> >> fine with that.
>> >>
>> >> Rob
>> >
>> > I cannot hardcode it into DT, because it is set by
>> > bootloader. And bootloader tell it to kernel via ATAGs
>> > structure. Bootloader is closed and proprietary and cannot
>> > be replaced (there is no documentation for hw init).
>>
>> Either the bootloader can put the serial number into the DTB
>> instead of ATAGs or the kernel decompressor can copy it from
>> ATAGs to DTB like is done already for other ATAGs. I presume
>> you cannot update the bootloader and will need the latter.
>>
>> Rob
>
> Rob, thanks for info! Btw, theoretically I can update bootloader
> if someone write it. So in practise I need to use second option.
>
> Can you tell me which CONFIG_ needs to be enabled for kernel
> decompressor (so it copy some ATAGs) and where to start looking
> at code (for adding new code for copying other ATAGs)?
See CONFIG_ARM_ATAG_DTB_COMPAT and arch/arm/boot/compressed/atags_to_fdt.c.
Rob
next prev parent reply other threads:[~2014-12-04 18:10 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-18 16:54 [PATCH] ARM: /proc/cpuinfo: Use DT machine name when possible Pali Rohár
2014-06-18 19:01 ` Russell King - ARM Linux
2014-06-18 19:09 ` Pali Rohár
2014-06-18 19:59 ` Russell King - ARM Linux
2014-06-19 8:21 ` Pavel Machek
2014-07-11 19:31 ` Pavel Machek
2014-06-18 19:07 ` Rob Herring
2014-06-18 19:22 ` Pali Rohár
2014-06-18 20:00 ` Russell King - ARM Linux
2014-06-18 20:20 ` Pali Rohár
2014-06-18 21:53 ` Fabio Estevam
2014-11-24 22:16 ` Pali Rohár
2014-06-18 20:46 ` Rob Herring
2014-06-18 21:47 ` Russell King - ARM Linux
2014-06-18 22:27 ` Rob Herring
2014-06-18 23:07 ` Russell King - ARM Linux
2014-11-24 22:19 ` Pali Rohár
2014-12-04 0:33 ` Rob Herring
2014-12-04 0:48 ` Pali Rohár
2014-12-04 16:49 ` Rob Herring
2014-12-04 17:57 ` Pali Rohár
2014-12-04 18:10 ` Rob Herring [this message]
2015-01-26 19:09 ` [PATCH] ARM: /proc/cpuinfo: DT: Add support for Revision Pali Rohár
2015-01-26 20:22 ` Rob Herring
2015-01-30 14:14 ` Pali Rohár
2015-01-30 21:03 ` Rob Herring
2015-02-27 15:45 ` Pali Rohár
2015-02-27 15:55 ` [PATCH v2 0/2] " Pali Rohár
2015-02-27 15:55 ` [PATCH v2 1/2] arm: devtree: Set system_rev from DT revision Pali Rohár
2015-02-27 15:55 ` [PATCH v2 2/2] arm: boot: convert ATAG_REVISION to DT revision field Pali Rohár
2015-03-02 11:28 ` [PATCH v2 0/2] ARM: /proc/cpuinfo: DT: Add support for Revision Pavel Machek
2015-03-16 15:44 ` Tony Lindgren
2015-03-16 16:14 ` Russell King - ARM Linux
2015-03-16 16:43 ` Nicolas Pitre
2015-03-16 19:21 ` Russell King - ARM Linux
2015-03-16 18:10 ` Tony Lindgren
2015-03-16 19:59 ` Russell King - ARM Linux
2015-03-16 20:54 ` Pali Rohár
2015-03-16 20:59 ` Tony Lindgren
2015-01-26 22:34 ` [PATCH] " Andreas Färber
2015-02-27 15:56 ` Pali Rohár
2015-01-26 19:16 ` [PATCH] ARM: /proc/atags: Export also for DT Pali Rohár
2015-01-26 20:33 ` Rob Herring
2015-01-27 13:21 ` Pavel Machek
2015-01-27 14:16 ` Rob Herring
2015-01-27 14:24 ` Pavel Machek
2015-01-27 14:32 ` Pali Rohár
2015-01-27 17:48 ` Russell King - ARM Linux
2015-01-27 20:03 ` Nicolas Pitre
2015-01-27 21:09 ` Russell King - ARM Linux
2015-01-27 21:34 ` Nicolas Pitre
2015-01-27 21:58 ` Nicolas Pitre
2015-01-27 22:33 ` Russell King - ARM Linux
2015-01-28 2:07 ` Nicolas Pitre
2015-01-28 6:21 ` Jean-Christophe PLAGNIOL-VILLARD
2015-01-28 7:19 ` Pavel Machek
2015-01-28 8:06 ` Jean-Christophe PLAGNIOL-VILLARD
2015-01-28 8:25 ` Pavel Machek
2015-01-28 7:18 ` Pavel Machek
2015-01-28 13:38 ` Pali Rohár
2015-01-27 23:10 ` Pavel Machek
2015-01-28 0:50 ` Tony Lindgren
2015-01-28 13:58 ` Pali Rohár
2015-01-28 14:33 ` Nicolas Pitre
2015-01-28 15:39 ` Tony Lindgren
2015-01-28 15:47 ` Pali Rohár
2015-01-28 15:48 ` Tony Lindgren
2015-01-28 16:31 ` Jason Cooper
2015-01-28 15:57 ` Rob Herring
2015-01-28 16:13 ` Russell King - ARM Linux
2015-01-28 16:19 ` Will Deacon
2015-01-28 17:01 ` Russell King - ARM Linux
2015-01-28 17:29 ` Russell King - ARM Linux
2015-01-28 17:18 ` Pali Rohár
2015-01-28 18:00 ` Jean-Christophe PLAGNIOL-VILLARD
2015-01-28 19:33 ` Pali Rohár
2015-01-28 18:03 ` Pavel Machek
2015-01-28 19:27 ` Arnd Bergmann
2015-01-28 14:46 ` Jean-Christophe PLAGNIOL-VILLARD
2015-01-27 19:40 ` Nicolas Pitre
2015-01-26 20:37 ` Russell King - ARM Linux
2015-01-26 20:44 ` Pali Rohár
2014-12-04 19:00 ` [PATCH] ARM: /proc/cpuinfo: Use DT machine name when possible Pali Rohár
2014-12-04 10:59 ` Russell King - ARM Linux
2014-06-18 21:10 ` Aaro Koskinen
2014-07-11 19:28 ` Pavel Machek
2014-11-24 22:21 ` Pali Rohár
2014-09-05 11:38 ` Pali Rohár
2014-09-05 12:13 ` Russell King - ARM Linux
2014-09-10 12:46 ` Pavel Machek
2014-11-24 22:23 ` Pali Rohár
2014-09-05 13:45 ` Mark Rutland
2014-09-05 13:52 ` Pali Rohár
2014-09-05 13:58 ` Mark Rutland
2014-11-24 22:25 ` Pali Rohár
2014-09-05 13:58 ` Fabio Estevam
2014-11-24 22:27 ` Pali Rohár
2014-09-06 15:34 ` Andreas Färber
2014-11-24 22:29 ` Pali Rohár
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