On Wed, 2023-03-15 at 12:19 +0200, Ville Syrjälä wrote:

On Wed, Mar 15, 2023 at 09:16:50AM +0100, Geert Uytterhoeven wrote:

quoted

Hi Niklas,

On Tue, Mar 14, 2023 at 1:13 PM Niklas Schnelle [off-list ref] wrote:

quoted

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!

quoted

--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig

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@@ -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.

I agree this "looks" like a nop but are we sure the inb() doesn't have
side effects? 
(for reference drivers/video/fbdev/aty/aty/atyfb_base.c:
atyfb_setup_generc() towards the end)

It does feel a bit out of scope for this series but if it's really a
nop nuking it surely is the cleaner solution.

Thanks,
Niklas