From: Javier Martinez Canillas <javier@osg.samsung.com>
To: "Pali Rohár" <pali.rohar@gmail.com>, "Tony Lindgren" <tony@atomide.com>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>,
Arnd Bergmann <arnd@arndb.de>,
Robin Murphy <robin.murphy@arm.com>,
Linus Walleij <linus.walleij@linaro.org>,
Ben Dooks <ben-linux@fluff.org>,
Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>,
Sebastian Reichel <sre@kernel.org>,
Aaro Koskinen <aaro.koskinen@iki.fi>, Pavel Machek <pavel@ucw.cz>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm: dt: Initialize boot_command_line from CONFIG_CMDLINE in case DT does not provide /chosen/bootargs
Date: Fri, 16 Dec 2016 09:13:34 -0300 [thread overview]
Message-ID: <029ec718-89c0-b08e-de7e-279946c1a9bd@osg.samsung.com> (raw)
In-Reply-To: <201612161246.12155@pali>
Hello Pali,
On 12/16/2016 08:46 AM, Pali Rohár wrote:
> On Thursday 15 December 2016 01:09:20 Pali Rohár wrote:
>> On Thursday 15 December 2016 00:52:24 Russell King - ARM Linux wrote:
>>> On Wed, Dec 14, 2016 at 10:12:43PM +0100, Pali Rohár wrote:
>>>> Commit 008a2ebcd677 ("ARM: dts: omap3: Remove skeleton.dtsi
>>>> usage") broke support for setting cmdline on Nokia N900 via
>>>> CONFIG_CMDLINE.
>>>>
>>>> It is because arm code booted in DT mode parse cmdline only via
>>>> function early_init_dt_scan_chosen() and that function does not
>>>> fill variable boot_command_line when DTB does not contain /chosen
>>>> entry. It is called from function early_init_dt_scan_nodes() in
>>>> setup_machine_fdt().
>>>>
>>>> This patch fixes it by explicitly filling boot_command_line in
>>>> function setup_machine_fdt() after calling
>>>> early_init_dt_scan_nodes() in case boot_command_line still
>>>> remains empty.
>>>
>>> This looks like a hack.
>>>
>>> First, the matter of the ATAGs compatibility. The decompressor
>>> relies on there being a pre-existing /chosen node to insert the
>>> command line and other parameters into. If we've dropped it (by
>>> dropping skeleton.dtsi) then we've just regressed more than just
>>> N900 - the decompressor won't be able to merge the ATAGs into the
>>> concatenated FDT.
>>
>> Hm... I did not think about it. But right this can be broken too...
>
> Tony, Javier: are you aware of above ↑↑↑ problem?
>
> It looks like commit 008a2ebcd677 ("ARM: dts: omap3: Remove
> skeleton.dtsi usage") should be really reverted.
>
I don't think reverting the mentioned commit is the correct fix for your
problem. We are trying to get rid of skeleton.dtsi for many reasons, see
commit commit ("3ebee5a2e141 arm64: dts: kill skeleton.dtsi").
Also, the chosen node is mentioned to be optional in the ePAPR document
and u-boot creates a chosen node if isn't found [0] so this issue is only
present in boards that don't use u-boot like the N900/N950/N9 phones.
So if NOLO doesn't do the same than u-boot and the kernel expects a chosen
node, I suggest to add an empty chosen node in the omap3-n900.dts and
omap3-n950-n9.dtsi device tree source files.
[0]: http://git.denx.de/?p=u-boot.git;a=blob;f=common/fdt_support.c;h=c9f7019e38e8de1469f506cdd57353fd27d8e134;hb=HEAD#l226
Best regards,
--
Javier Martinez Canillas
Open Source Group
Samsung Research America
next prev parent reply other threads:[~2016-12-16 12:13 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 21:12 [PATCH] arm: dt: Initialize boot_command_line from CONFIG_CMDLINE in case DT does not provide /chosen/bootargs Pali Rohár
2016-12-14 21:25 ` Pavel Machek
2016-12-14 21:46 ` Tony Lindgren
2016-12-14 22:22 ` Javier Martinez Canillas
2016-12-14 23:52 ` Russell King - ARM Linux
2016-12-15 0:09 ` Pali Rohár
2016-12-15 0:18 ` Robin Murphy
2016-12-15 10:09 ` Russell King - ARM Linux
2016-12-16 11:42 ` Pali Rohár
2016-12-25 22:08 ` Pali Rohár
2017-01-02 13:54 ` Russell King - ARM Linux
2016-12-16 11:46 ` Pali Rohár
2016-12-16 12:13 ` Javier Martinez Canillas [this message]
2016-12-16 12:32 ` Pali Rohár
2016-12-16 12:38 ` Javier Martinez Canillas
2016-12-16 12:48 ` Pali Rohár
2016-12-16 12:53 ` Javier Martinez Canillas
2016-12-16 15:40 ` Tony Lindgren
2016-12-16 16:13 ` Pali Rohár
2016-12-16 16:21 ` Tony Lindgren
2016-12-16 16:27 ` Russell King - ARM Linux
2016-12-16 16:57 ` Mark Rutland
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