Maarten Lankhorst b094fd12b9 drm/i915: Always recompute watermarks when distrust_bios_wm is set, v2. ...

commit 4e3aed8445 upstream.

On some systems there can be a race condition in which no crtc state is
added to the first atomic commit. This results in all crtc's having a
null DDB allocation, causing a FIFO underrun on any update until the
first modeset.

Changes since v1:
- Do not take the connection_mutex, this is already done below.

Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Inspired-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 98d39494d3 ("drm/i915/gen9: Compute DDB allocation at atomic
check time (v4)")
Cc: Mahesh Kumar <mahesh1.kumar@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170531154236.27180-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit 367d73d280)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

2017-06-17 06:44:18 +02:00

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