[Intel-gfx] [PATCH] drm/i915: Whitelist SLICE_COMMON_ECO_CHICKEN1 on Geminilake.

[Kenneth Graunke]

Geminilake requires the 3D driver to select whether barriers are
intended for compute shaders, or tessellation control shaders, by
whacking a "Barrier Mode" bit in SLICE_COMMON_ECO_CHICKEN1 when
switching pipelines.  Failure to do this properly can result in GPU
hangs.

Unfortunately, this means it needs to switch mid-batch, so only
userspace can properly set it.  To facilitate this, the kernel needs
to whitelist the register.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/i915/i915_reg.h        | 2 ++
 drivers/gpu/drm/i915/intel_engine_cs.c | 5 +++++
 2 files changed, 7 insertions(+)

Hello,

We unfortunately need to whitelist an extra register for GPU hang fix
on Geminilake.  Here's the corresponding Mesa patch:

https://patchwork.freedesktop.org/patch/196047/

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 966e4df9700e..505c605eff98 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7079,6 +7079,8 @@ enum {
 #define GEN9_SLICE_COMMON_ECO_CHICKEN0		_MMIO(0x7308)
 #define  DISABLE_PIXEL_MASK_CAMMING		(1<<14)
 
+#define GEN9_SLICE_COMMON_ECO_CHICKEN1		_MMIO(0x731c)
+
 #define GEN7_L3SQCREG1				_MMIO(0xB010)
 #define  VLV_B0_WA_L3SQCREG1_VALUE		0x00D30000
 
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index ebdcbcbacb3c..d64a9f907550 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1338,6 +1338,11 @@ static int glk_init_workarounds(struct intel_engine_cs *engine)
 	if (ret)
 		return ret;
 
+	/* Userspace needs to toggle "Barrier Mode" to avoid GPU hangs */
+	ret = wa_ring_whitelist_reg(engine, GEN9_SLICE_COMMON_ECO_CHICKEN1);
+	if (ret)
+		return ret;
+
 	/* WaToEnableHwFixForPushConstHWBug:glk */
 	WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
 			  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);
-- 
2.15.1