drm/i915/gsc: implement wa 14015076503
The WA states that we need to alert the GSC FW before doing a GSC engine
reset and then wait for 200ms. The GuC owns engine reset, so on the i915
side we only need to apply this for full GT reset.
Given that we do full GT resets in the resume paths to cleanup the HW
state and that a long wait in those scenarios would not be acceptable,
a faster path has been introduced where, if the GSC is idle, we try first
to individually reset the GuC and all engines except the GSC and only fall
back to full reset if that fails.
Note: according to the WA specs, if the GSC is idle it should be possible
to only wait for the uC wakeup time (~15ms) instead of the whole 200ms.
However, the GSC FW team have mentioned that the wakeup time can change
based on other things going on in the HW and pcode, so a good security
margin would be required. Given that when the GSC is idle we already
skip the wait & reset entirely and that this reduced wait would still
likely be too long to use in resume paths, it's not worth adding support
for this reduced wait.
v2: add comment to explain why it is safe to skip the GSC reset (John)
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: John Harrison <john.c.harrison@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323231857.2194435-2-daniele.ceraolospurio@intel.com
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index cf80500..818df42 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -923,8 +923,18 @@
#define DG1_GSC_HECI2_BASE 0x00259000
#define DG2_GSC_HECI1_BASE 0x00373000
#define DG2_GSC_HECI2_BASE 0x00374000
+#define MTL_GSC_HECI1_BASE 0x00116000
+#define MTL_GSC_HECI2_BASE 0x00117000
+#define HECI_H_CSR(base) _MMIO((base) + 0x4)
+#define HECI_H_CSR_IE REG_BIT(0)
+#define HECI_H_CSR_IS REG_BIT(1)
+#define HECI_H_CSR_IG REG_BIT(2)
+#define HECI_H_CSR_RDY REG_BIT(3)
+#define HECI_H_CSR_RST REG_BIT(4)
+#define HECI_H_GS1(base) _MMIO((base) + 0xc4c)
+#define HECI_H_GS1_ER_PREP REG_BIT(0)
#define HSW_GTT_CACHE_EN _MMIO(0x4024)
#define GTT_CACHE_EN_ALL 0xF0007FFF
