Re: [PATCH 00/19] drm/i915/overlay: Convert to parent interface

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 18 Feb 2026, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Split the overlay code into i915 vs. display parts and introduce
> and new parent interface for the display->i915 calls.
>
> The interface is rather verbose due to the interruptible ioctl
> design of the overlay code. Ideally we'd implement the overlay
> as a drm plane and tell it to flip via MMIO writes to OVADD,
> at which point the parent interface could be limited to just
> two functions to repartition the render cache as needed.
> Maybe one day...
>
> Smoke tested on i830 and i965gm.

I'm a bit sad how verbose the interface ended up being, especially
considering I was prepared to nuke the entire thing [1].

I reviewed this fairly lightly, commented in a few places, and I'm happy
enough with the end result, even if not thrilled. As always, I'm pretty
much trusting you to maintain and test this, as we don't have relevant
tests in IGT nor machines in CI, and we're not really getting bug
reports for the oldest platform anymore either.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

Along with the error pointer fix, the whole thing needs a rebase due to:

69050f8d6d07 ("treewide: Replace kmalloc with kmalloc_obj for non-scalar types")
bf4afc53b77a ("Convert 'alloc_obj' family to use the new default GFP_KERNEL argument")

from upstream.

[1] https://lore.kernel.org/r/20260204164827.807502-1-jani.nikula@intel.com


>
> Ville Syrjälä (19):
>   drm/i915/overlay: Remove GPU hang snapshot stuff
>   drm/i915/overlay: Track current frontbuffer_bits
>   drm/i915/overlay: Extract i915_overlay_is_active()
>   drm/i915/overlay: Remove redundant overlay->active
>   drm/i915/overlay: Relocate the underrun check
>   drm/i915/overlay: Introduce i915_overlay_obj_lookup()
>   drm/i915/overlay: Use struct drm_gem_object as the type
>   drm/i915/overlay: Extract i915_overlay_reset()
>   drm/i915/overlay: Extract i915_overlay_setup()
>   drm/i915/overlay: Extract i915_overlay_cleanup()
>   drm/i915/overlay: Abstract buffer (un)pinning
>   drm/i915/overlay: Rename low level i915 specific functions
>   drm/i915/overlay: Adjust i915 specific interfaces
>   drm/i915/overlay: Make i830_overlay_clock_gating() i915 specific
>   drm/i915/overlay: s/dev_priv/i915/
>   drm/i915/overlay: Split 'struct intel_overlay'
>   drm/i915/overlay: Don't use fetch_and_zero() in display code
>   drm/i915/overlay: Move i915 specific code into i915_overlay.c
>   drm/i915/overlay: Convert overlay to parent interface
>
>  drivers/gpu/drm/i915/Makefile                 |   1 +
>  .../gpu/drm/i915/display/intel_display_regs.h |   2 -
>  .../drm/i915/display/intel_display_snapshot.c |   4 -
>  drivers/gpu/drm/i915/display/intel_overlay.c  | 584 ++----------------
>  drivers/gpu/drm/i915/display/intel_overlay.h  |  48 --
>  drivers/gpu/drm/i915/display/intel_parent.c   |  76 +++
>  drivers/gpu/drm/i915/display/intel_parent.h   |  26 +
>  drivers/gpu/drm/i915/i915_driver.c            |   2 +
>  drivers/gpu/drm/i915/i915_drv.h               |   3 +
>  drivers/gpu/drm/i915/i915_overlay.c           | 517 ++++++++++++++++
>  drivers/gpu/drm/i915/i915_overlay.h           |  11 +
>  drivers/gpu/drm/i915/i915_reg.h               |   4 +
>  drivers/gpu/drm/xe/Makefile                   |   1 +
>  include/drm/intel/display_parent_interface.h  |  33 +
>  14 files changed, 726 insertions(+), 586 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/i915_overlay.c
>  create mode 100644 drivers/gpu/drm/i915/i915_overlay.h

-- 
Jani Nikula, Intel