Re: [PATCH v3 35/38] video: handle HAS_IOPORT dependencies

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Niklas Schnelle" <schnelle@linux.ibm.com>,
	linux-arch@vger.kernel.org, "Arnd Bergmann" <arnd@kernel.org>,
	linux-fbdev@vger.kernel.org, "Albert Ou" <aou@eecs.berkeley.edu>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Helge Deller" <deller@gmx.de>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	"Alan Stern" <stern@rowland.harvard.edu>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>
Subject: Re: [PATCH v3 35/38] video: handle HAS_IOPORT dependencies
Date: Wed, 15 Mar 2023 12:19:48 +0200	[thread overview]
Message-ID: <ZBGbxDWEhqr8hhgU@intel.com> (raw)
In-Reply-To: <CAMuHMdW4f8GJ-kFDPg6Ao=g3ZAXq79u9nUZ_dW1LonHu+vxk8Q@mail.gmail.com>

On Wed, Mar 15, 2023 at 09:16:50AM +0100, Geert Uytterhoeven wrote:
> Hi Niklas,
> 
> On Tue, Mar 14, 2023 at 1:13 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> > not being declared. We thus need to add HAS_IOPORT as dependency for
> > those drivers using them and guard inline code in headers.
> >
> > Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/video/fbdev/Kconfig
> > +++ b/drivers/video/fbdev/Kconfig
> 
> > @@ -1284,7 +1285,7 @@ config FB_ATY128_BACKLIGHT
> >
> >  config FB_ATY
> >         tristate "ATI Mach64 display support" if PCI || ATARI
> > -       depends on FB && !SPARC32
> > +       depends on FB && HAS_IOPORT && !SPARC32
> 
> On Atari, this works without ATARI_ROM_ISA, hence it must not depend
> on HAS_IOPORT.
> The only call to inb() is inside a section protected by #ifdef
> CONFIG_PCI. So:

That piece of code is a nop anyway. We immediately overwrite
clk_wr_offset with a hardcoded selection after the register reads.
So if you nuke that nop code then no IOPORT dependency required
at all.

> 
>     depends on FB && !SPARC32
>     depends on ATARI || HAS_IOPORT
> 
> >         select FB_CFB_FILLRECT
> >         select FB_CFB_COPYAREA
> >         select FB_CFB_IMAGEBLIT
> 
> 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

-- 
Ville Syrjälä
Intel