This is similar to a patch I wrote several months ago. It's been updated for the new FORCEWAKE_MT, and it also no longer clears the debug register as it may be helpful to get that for the error state. Also recommended by Chris Wilson, use WARN() instead of DRM_ERROR, so we can get a backtrace.
v2: replace POSTING_READ with I915_READ_NOTRACE(GTFIFODBG). Recommended by Chris Wilson Cc: Chris Wilson <[email protected]> Signed-off-by: Ben Widawsky <[email protected]> --- drivers/gpu/drm/i915/i915_drv.c | 16 ++++++++++++++-- 1 files changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 1658cfd..26b53eb 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -381,14 +381,26 @@ void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv) void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv) { + u32 gtfifodbg; + I915_WRITE_NOTRACE(FORCEWAKE, 0); - POSTING_READ(FORCEWAKE); + + /* The below doubles as a POSTING_READ */ + gtfifodbg = I915_READ_NOTRACE(GTFIFODBG); + WARN(gtfifodbg & GT_FIFO_CPU_ERROR_MASK, + "MMIO read or write has been dropped %x\n", gtfifodbg); } void __gen6_gt_force_wake_mt_put(struct drm_i915_private *dev_priv) { + u32 gtfifodbg; + I915_WRITE_NOTRACE(FORCEWAKE_MT, (1<<16) | 0); - POSTING_READ(FORCEWAKE_MT); + + /* The below doubles as a POSTING_READ */ + gtfifodbg = I915_READ_NOTRACE(GTFIFODBG); + WARN(gtfifodbg & GT_FIFO_CPU_ERROR_MASK, + "MMIO read or write has been dropped %x\n", gtfifodbg); } /* -- 1.7.9 _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
