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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Fri, 11 Mar 2022 10:13:36 +0100
Message-ID: <CAMuHMdU92K9ZLptwJPG_opA4Reg61ksOgQ-P+2niHX=bf306Kg@mail.gmail.com>
Subject: Re: [PATCH] tty: serial: bcm63xx: use more precise Kconfig symbol
To:     Florian Fainelli <f.fainelli@gmail.com>
Cc:     =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>,
        Kevin Cernekee <cernekee@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>,
        Arnd Bergmann <arnd@arndb.de>
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Hi Florian,

On Thu, Mar 10, 2022 at 10:49 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
> On 3/10/22 12:33 AM, Rafał Miłecki wrote:
> > On 10.03.2022 09:19, Geert Uytterhoeven wrote:
> >> On Thu, Mar 10, 2022 at 8:22 AM Rafał Miłecki <zajec5@gmail.com> wrote:
> >>> From: Rafał Miłecki <rafal@milecki.pl>
> >>>
> >>> Patches lowering SERIAL_BCM63XX dependencies led to a discussion and
> >>> documentation change regarding "depends" usage. Adjust Kconfig entry to
> >>> match current guidelines. Make this symbol available for relevant
> >>> architectures only.
> >>>
> >>> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> >>> Ref: f35a07f92616 ("tty: serial: bcm63xx: lower driver dependencies")
> >>> Ref: 18084e435ff6 ("Documentation/kbuild: Document platform
> >>> dependency practises")
> >>> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> >>
> >> Thanks for your patch!
> >>
> >>> --- a/drivers/tty/serial/Kconfig
> >>> +++ b/drivers/tty/serial/Kconfig
> >>> @@ -1100,7 +1100,8 @@ config SERIAL_TIMBERDALE
> >>>   config SERIAL_BCM63XX
> >>>          tristate "Broadcom BCM63xx/BCM33xx UART support"
> >>>          select SERIAL_CORE
> >>> -       depends on COMMON_CLK
> >>> +       depends on MIPS || ARM || ARM64 || COMPILE_TEST
> >>> +       default ARCH_BCM4908 || BCM63XX || BMIPS_GENERIC
> >>
> >> So ARCH_BCM4908 covers ARM64, and BCM63XX || BMIPS_GENERIC
> >> cover MIPS.  Is there some symbol covering ARM so we can change the
> >> depends to
> >>
> >>      depends on FOO || ARCH_BCM4908 || BCM63XX || BMIPS_GENERIC ||
> >> COMPILE_TEST
> >>
> >> ?
> >
> > Florian, Kevin: do you know what other platforms need that driver?
>
> Yes that would be ARCH_BCM_63XX.

Had to read this twice, before I realized this is different from BCM63XX.

As we already have

    drivers/char/hw_random/Kconfig:    ARCH_BCM_63XX || BCM63XX ||
BMIPS_GENERIC || COMPILE_TEST
    drivers/spi/Kconfig: depends on BCM63XX || BMIPS_GENERIC ||
ARCH_BCM_63XX || COMPILE_TEST

and drivers/tty/serial/Kconfig would be a third case, would it make
sense to unify BCM63XX and ARCH_BCM_63XX into a single symbol?
We already share several ARCH_* symbols between arm and arm64,
and I expect more will be shared with riscv in the future
(e.g. ARCH_RENESAS).

Or are MIPS BCM63xx and ARM BCM63xx too dissimilar?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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