linux-kernel - Re: [PATCH] tty: New RISC-V SBI console driver

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Date:   Fri, 8 Dec 2017 08:37:18 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Palmer Dabbelt <palmer@...ive.com>
Cc:     jslaby@...e.com, patches@...ups.riscv.org,
        linux-kernel@...r.kernel.org, Palmer Dabbelt <palmer@...belt.com>
Subject: Re: [PATCH] tty: New RISC-V SBI console driver

On Thu, Dec 07, 2017 at 04:10:15PM -0800, Palmer Dabbelt wrote:
> From: Palmer Dabbelt <palmer@...belt.com>
> 
> The RISC-V ISA defines a simple console that is availiable via SBI calls
> on all systems.  This patch adds a driver for this console interface
> that can act as both a target for early printk and as the system
> console.  The core arch code already enables the early printk support
> when CONFIG_HVC_RISCV_SBI is defined.
> 
> There is one checkpatch.pl warning here: to check the MAINTAINERS file.
> They're all matched by the "K: riscv" line.
> 
> Signed-off-by: Palmer Dabbelt <palmer@...belt.com>
> ---
>  arch/riscv/include/asm/hvc_riscv_sbi.h | 12 ++++++
>  drivers/tty/hvc/Kconfig                | 11 +++++
>  drivers/tty/hvc/Makefile               |  1 +
>  drivers/tty/hvc/hvc_riscv_sbi.c        | 75 ++++++++++++++++++++++++++++++++++
>  4 files changed, 99 insertions(+)
>  create mode 100644 arch/riscv/include/asm/hvc_riscv_sbi.h
>  create mode 100644 drivers/tty/hvc/hvc_riscv_sbi.c
> 
> diff --git a/arch/riscv/include/asm/hvc_riscv_sbi.h b/arch/riscv/include/asm/hvc_riscv_sbi.h
> new file mode 100644
> index 000000000000..41723ed7bd97
> --- /dev/null
> +++ b/arch/riscv/include/asm/hvc_riscv_sbi.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef _ASM_RISCV_HVC_RISCV_SBI_H
> +#define _ASM_RISCV_HVC_RISCV_SBI_H
> +
> +/*
> + * We always support CONFIG_EARLY_PRINTK via the SBI console driver because it
> + * works well enough that there's no penalty to doing so.
> + */
> +extern struct console riscv_sbi_early_console_dev __initdata;

Are you sure that __initdata should go into a .h file with an extern?

And why do you need this .h file?  Nothing in this patch uses it.

> +config HVC_RISCV_SBI
> +	bool "RISC-V SBI console support"
> +	depends on RISCV
> +	select HVC_DRIVER
> +	default y

Unless you can not boot your machine without this, you do not need 'y'.

thanks,

greg k-h