Patch "drm/i915: Whitelist SLICE_COMMON_ECO_CHICKEN1 on Geminilake." has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915: Whitelist SLICE_COMMON_ECO_CHICKEN1 on Geminilake.

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-whitelist-slice_common_eco_chicken1-on-geminilake.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Kenneth Graunke <[email protected]>
Date: Fri, 5 Jan 2018 00:59:05 -0800
Subject: drm/i915: Whitelist SLICE_COMMON_ECO_CHICKEN1 on Geminilake.

From: Kenneth Graunke <[email protected]>

commit 4636bda86aa1f34f45c629477476a0dcfa04e597 upstream.

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.

The workarounds page currently tags this as applying to Broxton only, but that doesn't make sense. The documentation for the register it references says the bit userspace is supposed to toggle only exists on Geminilake. Empirically, the Mesa patch to toggle this bit appears to fix intermittent GPU hangs in tessellation control shader barrier tests on Geminilake; we haven't seen those hangs on Broxton.

v2: Mention WA #0862 in the comment (it doesn't have a name).

---
 drivers/gpu/drm/i915/i915_reg.h        |    2 ++
 drivers/gpu/drm/i915/intel_engine_cs.c |    5 +++++
 2 files changed, 7 insertions(+)

@@ -6987,6 +6987,8 @@ 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
 

@@ -1125,6 +1125,11 @@ static int glk_init_workarounds(struct i
 	if (ret)
 		return ret;
 
+	/* WA #0862: Userspace has to set "Barrier Mode" to avoid 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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/drm-i915-whitelist-slice_common_eco_chicken1-on-geminilake.patch