drm/i915: Busy-spin wait_for condition in atomic contexts

During modesetting, we need to wait for the hardware to report
readiness by polling the registers. Normally, we call msleep() between
reads, because some state changes may take a whole vblank or more
to complete. However during a panic, we are in an atomic context and
cannot sleep. Instead, busy spin polling the termination condition.

References: https://bugzilla.kernel.org/show_bug.cgi?id=31772
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 5daa991cb28733149da4402b51ff01964731bc46..f5b0d8306d8372142f8c649f815a170d348be99e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -39,7 +39,7 @@
                        ret__ = -ETIMEDOUT;                             \
                        break;                                          \
                }                                                       \
-               if (W && !in_dbg_master()) msleep(W);                   \
+               if (W && !(in_atomic() || in_dbg_master())) msleep(W);  \
        }                                                               \
        ret__;                                                          \
 })