linux-kernel - Re: [PATCH v3 35/38] video: handle HAS

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Date:   Wed, 15 Mar 2023 12:19:48 +0200
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        linux-arch@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
        linux-fbdev@...r.kernel.org, Albert Ou <aou@...s.berkeley.edu>,
        Arnd Bergmann <arnd@...db.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Helge Deller <deller@....de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Alan Stern <stern@...land.harvard.edu>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Subject: Re: [PATCH v3 35/38] video: handle HAS_IOPORT dependencies

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@...ux.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@...nel.org>
> > Signed-off-by: Niklas Schnelle <schnelle@...ux.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@...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

-- 
Ville Syrjälä
Intel