drm/i915: Whitelist SLICE_COMMON_ECO_CHICKEN1 on Geminilake.

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).

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180105085905.9298-1-kenneth@whitecape.org

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 966e4df9700ec6cf6a9f7ce64439d8cc6c3ff4d6..505c605eff989240b1489f18f641926ba585bd37 100644 (file)
--- 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 ebdcbcbacb3c8673d8e142e9ddc53d601fc83b4c..6bb51a502b8b4e35a13908344c047d89f1f32c6a 100644 (file)
--- 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;
 
+       /* 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);