Re: [PATCH v6 3/5] drm: handle HAS_IOPORT dependencies

[Arnd Bergmann]

On Mon, Oct 7, 2024, at 14:39, Lucas De Marchi wrote:
> as an example:
> $ git grep -lw outb -- drivers/gpu/drm/
> drivers/gpu/drm/gma500/cdv_device.c
> drivers/gpu/drm/i915/display/intel_vga.c
> drivers/gpu/drm/qxl/qxl_cmd.c
> drivers/gpu/drm/qxl/qxl_irq.c
> drivers/gpu/drm/tiny/bochs.c
> drivers/gpu/drm/tiny/cirrus.c
>
> you are adding the dependency on xe, but why are you keeping i915 out?
> What approach did you use to determine the dependency?

I did a lot of 'randconfig' build testing on earlier versions
(and this version) of the series, which eventually catches
all of them. The i915 driver depends on CONfIG_X86 since it
is only used in Intel PC chipsets that already rely on PIO.

The XE driver is also used for add-on cards, so the drivers
can be built on all architectures including those that do
not support PCI I/O space access. Adding the dependency on
i915 as well wouldn't be wrong, but is not required for
correctness.

I also sent a patch for vmwgfx, which can be used on arm64.
arm64 currently always sets HAS_IOPORT, so my patch is not
required as a dependency for [PATCH v6 5/5], but we eventually
want this so HAS_IOPORT can become optional on arm64.

      Arnd