linux-kernel - Re: [PATCH v2 08/18] serial: intel: Get serial id from dts

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Date:   Tue, 7 Aug 2018 09:33:38 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     songjun.wu@...ux.intel.com
Cc:     hua.ma@...ux.intel.com, yixin.zhu@...ux.intel.com,
        chuanhua.lei@...ux.intel.com, qi-ming.wu@...el.com,
        Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Greg KH <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jiri Slaby <jslaby@...e.com>
Subject: Re: [PATCH v2 08/18] serial: intel: Get serial id from dts

Hi Songjun,

On Fri, Aug 3, 2018 at 5:04 AM Songjun Wu <songjun.wu@...ux.intel.com> wrote:
> Get serial id from dts.
>
> "#ifdef CONFIG_LANTIQ" preprocessor is used because LTQ_EARLY_ASC
> macro is defined in lantiq_soc.h.
> lantiq_soc.h is in arch path for legacy product support.
>
> arch/mips/include/asm/mach-lantiq/xway/lantiq_soc.h
>
> If "#ifdef preprocessor" is changed to
> "if (IS_ENABLED(CONFIG_LANTIQ))", when CONFIG_LANTIQ is not enabled,
> code using LTQ_EARLY_ASC is compiled.
> Compilation will fail for no LTQ_EARLY_ASC defined.
>
> Signed-off-by: Songjun Wu <songjun.wu@...ux.intel.com>

Thanks for your patch!

> @@ -699,9 +700,19 @@ lqasc_probe(struct platform_device *pdev)
>                 return -ENODEV;
>         }
>
> -       /* check if this is the console port */
> -       if (mmres->start != CPHYSADDR(LTQ_EARLY_ASC))
> -               line = 1;
> +       /* get serial id */
> +       line = of_alias_get_id(node, "serial");
> +       if (line < 0) {
> +#ifdef CONFIG_LANTIQ
> +               if (mmres->start == CPHYSADDR(LTQ_EARLY_ASC))
> +                       line = 0;
> +               else
> +                       line = 1;
> +#else
> +               dev_err(&pdev->dev, "failed to get alias id, errno %d\n", line);
> +               return line;

Please note that not providing a fallback here makes life harder when using
DT overlays.
See the description of commit 7678f4c20fa7670f ("serial: sh-sci: Add support
for dynamic instances") for background info.

> +#endif
> +       }
>
>         if (lqasc_port[line]) {
>                 dev_err(&pdev->dev, "port %d already allocated\n", line);

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds