linux-kernel - Re: [PATCH 00/11] drm: Restore helper usability

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Message-ID: <CAMuHMdWb5sqhk1m4kD_72k0OzB5MTEFcP+QHFo+4rs8j8WEzPQ@mail.gmail.com>
Date: Mon, 22 Apr 2024 20:02:16 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: Arnd Bergmann <arnd@...db.de>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	Dave Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, 
	Linux-Renesas <linux-renesas-soc@...r.kernel.org>, Masahiro Yamada <masahiroy@...nel.org>, 
	linux-kbuild <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH 00/11] drm: Restore helper usability

Hi Jani,

On Mon, Apr 22, 2024 at 7:15 PM Jani Nikula <jani.nikula@...ux.intel.com> wrote:
> On Mon, 22 Apr 2024, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Mon, Apr 22, 2024 at 3:55 PM Arnd Bergmann <arnd@...db.de> wrote:
> >> I'm not sure where this misunderstanding comes from, as you
> >> seem to be repeating the same incorrect assumption about
> >> how select works that Maxime wrote in his changelog. To clarify,
> >> this works exactly as one would expect:
> >>
> >> config HELPER_A
> >>        tristate
> >>
> >> config HELPER_B
> >>        tristate
> >>        select HELPER_A
> >>
> >> config DRIVER
> >>        tristate "Turn on the driver and the helpers it uses"
> >>        select HELPER_B # this recursively selects HELPER_A
> >>
> >> Whereas this one is broken:
> >>
> >> config FEATURE_A
> >>        tristate "user visible if I2C is enabled"
> >>        depends on I2C
> >>
> >> config HELPER_B
> >>        tristate # hidden
> >>        select FEATURE_A
> >>
> >> config DRIVER
> >>        tristate "This driver is broken if I2C is disabled"
> >>        select HELPER_B
> >
> > So the DRIVER section should gain a "depends on I2C" statement.
>
> Why should DRIVER have to care that HELPER_B needs either FEATURE_A or
> I2C? It should only have to care about HELPER_B. And if the dependencies
> of FEATURE_A or HELPER_B later change, that's their business, not
> DRIVER's.

That's correct. But currently the dependency on I2C is not handled
automatically.

> > Yamada-san: would it be difficult to modify Kconfig to ignore symbols
> > like DRIVER that select other symbols with unmet dependencies?
> > Currently it already warns about that.
> >
> > Handling this implicitly (instead of the current explict "depends
> > on") would have the disadvantage though: a user who is not aware of
> > the implicit dependency may wonder why DRIVER is invisible in his
> > config interface.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg

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