[Intel-gfx] [PATCH 10/10] drm/i915: Support variable cursor height on ivb+

[Chris Wilson]

On Tue, Mar 07, 2017 at 05:27:09PM +0200, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> IVB introduced the CUR_FBC_CTL register which allows reducing the cursor
> height down to 8 lines from the otherwise square cursor dimensions.
> Implement support for it. CUR_FBC_CTL can't be used when the cursor
> is rotated.
> 
> Commandeer the otherwise unused cursor->cursor.size to track the
> current value of CUR_FBC_CTL to optimize away redundant CUR_FBC_CTL
> writes, and to notice when we need to arm the update via CURBASE if
> just CUR_FBC_CTL changes.

For userspace to discover this, they should just use trial and error
during startup (using the legacy SetCursor)? Though the easiest way
would cause the cursor to flicker - just hope the cursor is
off/invisible on startup.

Code makes a lot of sense after all the refactoring, but I'll leave the
register checking to somebody else unless they are lazier than I am.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre