[PATCH] drm/xe: Remove unused "mmio_ext" code

[Lucas De Marchi]

On Mon, Jan 06, 2025 at 03:43:13PM -0800, Matt Roper wrote:
>The "mmio_ext" and 'REG_EXT" code is currently unused on any existing
>platform.  Going forward, this also isn't the design we want to use for
>any future platforms/features either, so we should just go ahead and
>remove the dead code to avoid confusion.
>
>mmio_ext was originally added in an attempt to hack around the early
>(mis)design of the Xe driver, which used xe_gt as the target for all
>register MMIO access, even those completely unrelated to the GT subunit
>of the hardware.  With the introduction of commit 34953ee349dd ("drm/xe:
>Create dedicated xe_mmio structure") and its follow-up patches, that
>misdesign has been corrected and access to register MMIO regions
>specific to hardware units is now done through xe_mmio structures which
>encapsulate an iomap, region size, and some other metadata.
>
>Although all of the registers used by the driver today happen to fall
>within one specific PCI BAR region, and thus re-use a single device-wide
>iomap, there's no requirement that this stay true for future platforms
>or features.  I.e., if a future platform adds a new 'foo' hardware unit
>that exists at a different area in the BAR, or even in a completely
>different BAR, then that would be handled by doing a separate iomap of
>that unit's register region and wrapping it in its own 'struct xe_mmio
>foo_regs' structure.  The pointer to the new 'foo_regs' could be placed
>within the xe_device, xe_tile, xe_gt, etc., according to where the new
>hardware unit falls within the current hardware hierarchy.
>
>This effectively reverts the following commits, although parts of these
>commits had already vanished or changed with the earlier xe_mmio
>refactor work:
>
> - commit 399a13323f0d ("drm/xe: add 28-bit address support in struct
>   xe_reg")
> - commit fdef72e02e20 ("drm/xe: add a flag to bypass multi-tile config
>   from MTCFG reg")
> - commit 866b2b176434 ("drm/xe: add MMIO extension support flags")
> - commit ef29b390c734 ("drm/xe: map MMIO BAR according to the num of
>   tiles in device desc")
> - commit a4e2f3a299ea ("drm/xe: refactor xe_mmio_probe_tiles to support
>   MMIO extension")
>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>Cc: Koby Elbaz <kelbaz at habana.ai>
>Signed-off-by: Matt Roper <matthew.d.roper at intel.com>

Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>, but let's wait
a day or 2 to give a chance for others to take another look.

Koby, can you ack this?

thanks
Lucas De Marchi