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
WARNING: multiple messages have this Message-ID (diff)
From: 'Krzysztof Kozlowski' <krzk@kernel.org>
To: Alim Akhtar <alim.akhtar@samsung.com>
Cc: robh+dt@kernel.org, devicetree@vger.kernel.org,
linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.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
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-07-05 18:09 UTC|newest]
Thread overview: 10+ 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 18:25 ` Alim Akhtar
2020-07-03 18:49 ` Alim Akhtar
2020-07-03 18:49 ` Alim Akhtar
2020-07-04 10:22 ` Krzysztof Kozlowski
2020-07-04 10:22 ` Krzysztof Kozlowski
2020-07-05 1:39 ` Alim Akhtar
2020-07-05 1:39 ` Alim Akhtar
2020-07-05 18:09 ` 'Krzysztof Kozlowski' [this message]
2020-07-05 18:09 ` 'Krzysztof Kozlowski'
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