drm/i915/lmem: Fail driver init if LMEM training failed

Boot firmware performs memory training and health assessment during
startup.  If the memory training fails, the firmware will consider the
GPU unusable and will instruct the punit to keep the GT powered down.
If this happens, our driver will be unable to communicate with the GT
(all GT registers will read back as 0, forcewake requests will timeout,
etc.) so we should abort driver initialization if this happens.  We can
confirm that LMEM was initialized successfully via sgunit register
GU_CNTL.

Bspec: 53111
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Cc: Caz Yokoyama <Caz.Yokoyama@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210420131842.164163-5-matthew.auld@intel.com

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e087bcd..f414749 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -487,6 +487,9 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define GAB_CTL                                _MMIO(0x24000)
 #define   GAB_CTL_CONT_AFTER_PAGEFAULT (1 << 8)
 
+#define GU_CNTL                                _MMIO(0x101010)
+#define   LMEM_INIT                    REG_BIT(7)
+
 #define GEN6_STOLEN_RESERVED           _MMIO(0x1082C0)
 #define GEN6_STOLEN_RESERVED_ADDR_MASK (0xFFF << 20)
 #define GEN7_STOLEN_RESERVED_ADDR_MASK (0x3FFF << 18)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index ed5abe7..b4aaf8b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1917,6 +1917,18 @@ int intel_uncore_init_mmio(struct intel_uncore *uncore)
        if (ret)
                return ret;
 
+       /*
+        * The boot firmware initializes local memory and assesses its health.
+        * If memory training fails, the punit will have been instructed to
+        * keep the GT powered down; we won't be able to communicate with it
+        * and we should not continue with driver initialization.
+        */
+       if (IS_DGFX(i915) &&
+           !(__raw_uncore_read32(uncore, GU_CNTL) & LMEM_INIT)) {
+               drm_err(&i915->drm, "LMEM not initialized by firmware\n");
+               return -ENODEV;
+       }
+
        if (INTEL_GEN(i915) > 5 && !intel_vgpu_active(i915))
                uncore->flags |= UNCORE_HAS_FORCEWAKE;