drm/i915: Add SCRATCH1 and ROW_CHICKEN3 to the register whitelist.
authorFrancisco Jerez <currojerez@riseup.net>
Fri, 29 May 2015 13:44:15 +0000 (16:44 +0300)
committerDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 15 Jun 2015 10:34:58 +0000 (12:34 +0200)
commitd351f6d94893f3ba98b1b20c5ef44c35fc1da124
tree7c003f25e83919870f106b6ff9c3f2edf11dec6e
parent4e86f725cebc8164e5f6601707379dd51440269d
drm/i915: Add SCRATCH1 and ROW_CHICKEN3 to the register whitelist.

Only bit 27 of SCRATCH1 and bit 6 of ROW_CHICKEN3 are allowed to be
set because of security-sensitive bits we don't want userspace to mess
with.  On HSW hardware the whitelisted bits control whether atomic
read-modify-write operations are performed on L3 or on GTI, and when
set to L3 (which can be 10x-30x better performing than on GTI,
depending on the application) require great care to avoid a system
hang, so we currently program them to be handled on GTI by default.

Beignet can immediately start taking advantage of this change to
enable L3 atomics.  Mesa should eventually switch to L3 atomics too,
but a number of non-trivial changes are still required so it will
continue using GTI atomics for now.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Zhigang Gong <zhigang.gong@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
drivers/gpu/drm/i915/i915_cmd_parser.c