Messages in this thread | | | Subject | Re: [PATCH] MIPS: Loongson: Add support for serial console | From | WANG Xuerui <> | Date | Mon, 18 May 2020 10:36:55 +0800 |
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On 2020/5/18 09:08, Tiezhu Yang wrote:
> On 05/16/2020 07:09 PM, WANG Xuerui wrote: >> On 5/16/20 3:03 PM, Tiezhu Yang wrote: >> >>> After commit 87fcfa7b7fe6 ("MIPS: Loongson64: Add generic dts"), >>> there already exists the node and property of Loongson CPU UART0 >>> in loongson3-package.dtsi: >>> >>> cpu_uart0: serial@1fe001e0 { >>> compatible = "ns16550a"; >>> reg = <0 0x1fe001e0 0x8>; >>> clock-frequency = <33000000>; >>> interrupt-parent = <&liointc>; >>> interrupts = <10 IRQ_TYPE_LEVEL_HIGH>; >>> no-loopback-test; >>> }; >>> >>> In order to support for serial console on the Loongson platform, >>> add CONFIG_SERIAL_OF_PLATFORM=y to loongson3_defconfig. >>> >>> With this patch, we can see the following boot message: >>> >>> [ 1.877745] printk: console [ttyS0] disabled >>> [ 1.881979] 1fe001e0.serial: ttyS0 at MMIO 0x1fe001e0 (irq = 16, >>> base_baud = 2062500) is a 16550A >>> [ 1.890838] printk: console [ttyS0] enabled >>> >>> And also, we can login normally from the serial console. >>> >>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> >>> --- >>> >>> Hi Jiaxun, >>> >>> Thank you very much for your suggestion. >>> >>> arch/mips/configs/loongson3_defconfig | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/arch/mips/configs/loongson3_defconfig >>> b/arch/mips/configs/loongson3_defconfig >>> index 6768c16..cd95f08 100644 >>> --- a/arch/mips/configs/loongson3_defconfig >>> +++ b/arch/mips/configs/loongson3_defconfig >>> @@ -217,6 +217,7 @@ CONFIG_SERIAL_8250_EXTENDED=y >>> CONFIG_SERIAL_8250_MANY_PORTS=y >>> CONFIG_SERIAL_8250_SHARE_IRQ=y >>> CONFIG_SERIAL_8250_RSA=y >>> +CONFIG_SERIAL_OF_PLATFORM=y >>> CONFIG_HW_RANDOM=y >>> CONFIG_RAW_DRIVER=m >>> CONFIG_I2C_CHARDEV=y >> >> Hi, >> >> The patch title is again exaggerating things. This is a defconfig >> change, so please refer to `git log` output of `arch/mips/configs` >> and use something like "MIPS: Loongson: loongson3_defconfig: enable >> serial console" or "MIPS: Loongson: enable serial console in >> defconfig". The current title reads as if Loongson kernels never were >> able to use a serial console in the past. > > Hi Xuerui, > > Thanks for your suggestion. > > We can not use the serial console without this patch, > so I use the current patch subject.
One can always use their own config to build in whatever support they want. Only people blindly following defconfig are affected. That's why I think the original patch title is exaggerating.
> > Anyway, let me modify the patch subject to make it more accurate, > I think the following is better: > "MIPS: Loongson: Enable devicetree based probing for 8250 ports" > > drivers/tty/serial/8250/Kconfig: > config SERIAL_OF_PLATFORM > tristate "Devicetree based probing for 8250 ports" > > I will send v2 later. > No problem. Just make it clear that these are defconfig changes so people don't misunderstand, even if they're otherwise unfamiliar with the current state of things. > Thanks, > Tiezhu Yang >
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