| Message ID | 1426501710-24177-4-git-send-email-javier.martinez@collabora.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, Am 16.03.2015 um 11:28 schrieb Javier Martinez Canillas: > The kernel can use as the default console a serial port if is defined "The kernel can use a serial port as the default console if it's defined ..." > as stdout device in the Device Tree. > > This allows a board to be booted without the need of having a console > parameter in the kernel command line. > > Currently the Spring DTS has bootargs in the /chosen node and this is > kept since users that don't have a serial console on this board might > be using it to have the boot log shown in the display. This will have > more precedence than the stdout-path but it's fine since is only used "since it's" > when CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND is enabled. > > Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> > --- > arch/arm/boot/dts/exynos5250-spring.dts | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/boot/dts/exynos5250-spring.dts b/arch/arm/boot/dts/exynos5250-spring.dts > index f02775487cd4..b9ec763a5602 100644 > --- a/arch/arm/boot/dts/exynos5250-spring.dts > +++ b/arch/arm/boot/dts/exynos5250-spring.dts > @@ -25,6 +25,7 @@ > > chosen { > bootargs = "console=tty1"; > + stdout-path = "serial3:115200n8"; Is this a guess or did you verify that against some schematics? > }; > > gpio-keys { Assuming that bootargs still work, Reviewed-by: Andreas Färber <afaerber@suse.de> I do wonder why this mechanism could not point to the same location as bootargs? ("dp-controller"?) The device does not even have screws for opening it, so accessing the serial port is highly theoretical. Regards, Andreas
Hello Andreas, >> index f02775487cd4..b9ec763a5602 100644 >> --- a/arch/arm/boot/dts/exynos5250-spring.dts >> +++ b/arch/arm/boot/dts/exynos5250-spring.dts >> @@ -25,6 +25,7 @@ >> >> chosen { >> bootargs = "console=tty1"; >> + stdout-path = "serial3:115200n8"; > > Is this a guess or did you verify that against some schematics? > I don't have access to the Spring schematics but it is based on what is defined in the vendor u-boot for Spring [0]. There isn't a Spring specific configuration file but only a chromeos_daisy.h which is shared by Snow, Spring and Kate (not yet in mainline): #define CONFIG_DIRECT_BOOTARGS \ "console=ttySAC3," STRINGIFY(CONFIG_BAUDRATE) " debug earlyprintk" So I assumed that all daisy-based Chromebooks use the same UART for debug. >> }; >> >> gpio-keys { > > Assuming that bootargs still work, > Yes, the semantics are not changed. The std-out property is only used as a default if no console= parameter is passed so if you already are passing one in your bootloader or using the one defined in the /chosen bootargs by enabling CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND, that will be used instead of std-out. > Reviewed-by: Andreas Färber <afaerber@suse.de> > > I do wonder why this mechanism could not point to the same location as > bootargs? ("dp-controller"?) The device does not even have screws for I did wonder the same indeed but I don't know if you can use a display as std-out or only works for serial consoles. > opening it, so accessing the serial port is highly theoretical. > I see, in that case I think we could just drop this patch if is not possible to have a serial console even with some soldering like is the case in Snow, Peach Pit and Peach Pi. > Regards, > Andreas > Best regards, Javier [0]: https://chromium.googlesource.com/chromiumos/third_party/u-boot/+/firmware-spring-3824.B/include/configs/chromeos_daisy.h -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03/16/15 20:28, Javier Martinez Canillas wrote: > Hello Andreas, > Hi, >>> index f02775487cd4..b9ec763a5602 100644 >>> --- a/arch/arm/boot/dts/exynos5250-spring.dts >>> +++ b/arch/arm/boot/dts/exynos5250-spring.dts >>> @@ -25,6 +25,7 @@ >>> >>> chosen { >>> bootargs = "console=tty1"; >>> + stdout-path = "serial3:115200n8"; >> >> Is this a guess or did you verify that against some schematics? >> > > I don't have access to the Spring schematics but it is based on what > is defined in the vendor u-boot for Spring [0]. > > There isn't a Spring specific configuration file but only a > chromeos_daisy.h which is shared by Snow, Spring and Kate (not yet in > mainline): > > #define CONFIG_DIRECT_BOOTARGS \ > "console=ttySAC3," STRINGIFY(CONFIG_BAUDRATE) " debug earlyprintk" > > So I assumed that all daisy-based Chromebooks use the same UART for debug. > >>> }; >>> >>> gpio-keys { >> >> Assuming that bootargs still work, >> > > Yes, the semantics are not changed. The std-out property is only used > as a default if no console= parameter is passed so if you already are > passing one in your bootloader or using the one defined in the /chosen > bootargs by enabling CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND, that > will be used instead of std-out. > >> Reviewed-by: Andreas Färber <afaerber@suse.de> >> >> I do wonder why this mechanism could not point to the same location as >> bootargs? ("dp-controller"?) The device does not even have screws for > > I did wonder the same indeed but I don't know if you can use a display > as std-out or only works for serial consoles. > >> opening it, so accessing the serial port is highly theoretical. >> > > I see, in that case I think we could just drop this patch if is not > possible to have a serial console even with some soldering like is the > case in Snow, Peach Pit and Peach Pi. > I've applied this whole series so if you guys find any problem on this, please let me know ;) Thanks, Kukjin -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/boot/dts/exynos5250-spring.dts b/arch/arm/boot/dts/exynos5250-spring.dts index f02775487cd4..b9ec763a5602 100644 --- a/arch/arm/boot/dts/exynos5250-spring.dts +++ b/arch/arm/boot/dts/exynos5250-spring.dts @@ -25,6 +25,7 @@ chosen { bootargs = "console=tty1"; + stdout-path = "serial3:115200n8"; }; gpio-keys {
The kernel can use as the default console a serial port if is defined as stdout device in the Device Tree. This allows a board to be booted without the need of having a console parameter in the kernel command line. Currently the Spring DTS has bootargs in the /chosen node and this is kept since users that don't have a serial console on this board might be using it to have the boot log shown in the display. This will have more precedence than the stdout-path but it's fine since is only used when CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND is enabled. Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> --- arch/arm/boot/dts/exynos5250-spring.dts | 1 + 1 file changed, 1 insertion(+)