linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: 'Krzysztof Kozlowski' <krzk@kernel.org>
To: Alim Akhtar <alim.akhtar@samsung.com>
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
	robh+dt@kernel.org
Subject: Re: [PATCH] arm64: dts: exynos: Add minimal bootargs
Date: Sun, 5 Jul 2020 20:09:44 +0200	[thread overview]
Message-ID: <20200705180944.GB2765@kozik-lap> (raw)
In-Reply-To: <004c01d6526d$18c365e0$4a4a31a0$@samsung.com>

On Sun, Jul 05, 2020 at 07:09:14AM +0530, Alim Akhtar wrote:
> Hi Krzysztof,
> > Also, why did you use different serial for console?
> > 
> Once UART driver gets probed then console changes to ttySAC0. In case I am using stdout-path only,
> after bootconsole is disabled, kernel logs re-start printing from beginning (which might be expected behaviour?)
> 
> [    0.012416] printk: console [tty0] enabled
> [    0.016491] printk: bootconsole [exynos4210] disabled
> [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd032]
> [    0.000000] Linux version 5.8.0-rc3-next-20200703-00008-g4af626444f4a-dirty (alim@alim) (aarch64-linux-gnu-gcc (Linaro GCC 7.4-2019.02) 7.4.1 20181213 [l0
> [    0.000000] Machine model: Samsung Exynos7 Espresso board based on Exynos7
> 

No, this is not desired. The fix for it should not be redefining the
console to wrong argument.

For example on Odroid MC1 this problem does not exist:

[    0.000000] earlycon: exynos4210 at MMIO 0x12c20000 (options '115200n8')
[    0.000000] printk: bootconsole [exynos4210] enabled
[    3.111883] printk: console [ttySAC2] enabled
[    3.111883] printk: console [ttySAC2] enabled
[    3.120102] printk: bootconsole [exynos4210] disabled
[    3.120102] printk: bootconsole [exynos4210] disabled


but your console for some reason is tty0... why? Is your console
ttySAC2? Maybe it is the effect of alias:
serial0 = &serial_2;

> > However the question is, are you sure you want earlycon on every, including
> > successful boot? On most of the boards we do not enable by default. If
> > developer needs, he can choose it for example via U-Boot "setenv opts
> > earlycon".
> > 
> Using U-Boot is not the case always, any bootload can be used to boot the Linux, currently I am Coreboot.
> And 'earlycon' is not setup by default.
> As Espresson board is development board, IMO it is ok to keep it enable all the time, this helps in quickly knowing what going on incase boot fails early.
> Let me know if it is ok to keep " console=ttySAC0,115200n8" or shell I just re-spin with only 'earlycon'? or any other suggestion?

It should be just earlycon.

Best regards,
Krzysztof


      reply	other threads:[~2020-07-05 18:09 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200703184543epcas5p4adb3db7693094c72477b8469d9f205ba@epcas5p4.samsung.com>
2020-07-03 18:25 ` [PATCH] arm64: dts: exynos: Add minimal bootargs Alim Akhtar
2020-07-03 18:49   ` Alim Akhtar
2020-07-04 10:22     ` Krzysztof Kozlowski
2020-07-05  1:39       ` Alim Akhtar
2020-07-05 18:09         ` 'Krzysztof Kozlowski' [this message]

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=20200705180944.GB2765@kozik-lap \
    --to=krzk@kernel.org \
    --cc=alim.akhtar@samsung.com \
    --cc=devicetree@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-samsung-soc@vger.kernel.org \
    --cc=robh+dt@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).