drm/i915: Fix bw atomic check when switching between SAGV vs. no SAGV
commit ec663bca upstream. If the only thing that is changing is SAGV vs. no SAGV but the number of active planes and the total data rates end up unchanged we currently bail out of intel_bw_atomic_check() early and forget to actually compute the new WGV point mask and thus won't actually enable/disable SAGV as requested. This ends up poorly if we end up running with SAGV enabled when we shouldn't. Usually ends up in underruns. To fix this let's go through the QGV point mask computation if either the data rates/number of planes, or the state of SAGV is changing. v2: Check more carefully if things are changing to avoid the extra calculations/debugs from introducing unwanted overhead Cc: stable@vger.kernel.org Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> #v1 Fixes: 20f505f2 ("drm/i915: Restrict qgv points which don't have enough bandwidth.") Signed-off-by:Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220218064039.12834-3-ville.syrjala@linux.intel.com (cherry picked from commit 6b728595 ) Signed-off-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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