[Intel-gfx] [RFC 0/3] drm/i915: split display from drm_i915_private and i915_drv.h

[Matt Roper]

On Tue, Sep 26, 2023 at 08:15:40PM +0300, Jani Nikula wrote:
> We've been gradually separating display code from the rest of the i915
> driver code over the past few years. We can't get much further than this
> without some more drastic changes.
> 
> One of them is separating struct drm_i915_private and struct
> intel_display almost completely. The former would remain for core driver
> code and gem, while the latter would be for display. Long term, i915
> display code would not include i915_drv.h, and would not have access to
> struct drm_i915_private definion.
> 
> For display code, struct drm_i915_private would be opaque, and for the
> rest of the driver, struct intel_display would be opaque.
> 
> Naturally, such separation helps the upcoming xe driver integration with
> i915 display code. It's basically a requirement if (and that's still an
> if) we decide to use aux-bus to have a i915.ko/xe.ko <->
> intel-display.ko split. Regardless of that, I think this is a big
> maintainability plus on its own too. The everything-includes-everything
> model is really a nightmare.
> 
> Here are some draft ideas how this could be started. It will be a lot of
> churn especially in the display code, but I believe the end result will
> be cleaner.

I'm guessing the plan is also to pass some kind of 'ops' callback
structure down to intel_display when initializing a new device that it
can use when it needs general functionality from the base driver
(runtime PM, lowest-level register access, various memory management
stuff, etc.)?

In general, I'm very much in favor of making intel_display
self-contained with no direct access to drm_i915_private / xe_device,
and no direct calls outside of the display code.  I've been hoping we'd
find the time to start moving in that direction.


Matt

> 
> BR,
> Jani.
> 
> 
> Jani Nikula (3):
>   drm/i915: rough ideas for further separating display code from the
>     rest
>   drm/i915/hdmi: drafting what struct intel_display usage would look
>     like
>   drm/i915: draft what feature test macros would look like
> 
>  .../gpu/drm/i915/display/intel_display_core.h    | 16 ++++++++++++++++
>  .../gpu/drm/i915/display/intel_display_device.c  | 13 +++++++++++++
>  .../gpu/drm/i915/display/intel_display_device.h  |  4 ++++
>  drivers/gpu/drm/i915/display/intel_hdmi.c        | 15 ++++++++++-----
>  drivers/gpu/drm/i915/i915_drv.h                  | 11 ++++++++++-
>  5 files changed, 53 insertions(+), 6 deletions(-)
> 
> -- 
> 2.39.2
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation