[PATCH v4 4/4] drm/i915/dg2: Implement Wa_14022698537

[Raag Jadav]

G8 power state entry is disabled due to a limitation on DG2, so we
enable it from driver with Wa_14022698537. For now we enable it for
all DG2 devices with the exception of a few, for which, we enable
only when paired with whitelisted CPU models. This works with native
ASPM and reduces idle power consumption.

$ echo powersave > /sys/module/pcie_aspm/parameters/policy
$ lspci -s 0000:03:00.0 -vvv
LnkCtl: ASPM L1 Enabled; RCB 64 bytes, Disabled- CommClk-

v2: Fix Wa_ID and include it in subject (Badal)
    Rephrase commit message (Jani)
v3: Move workaround to i915_pcode_init() (Badal, Anshuman)
    Re-order macro (Riana)
v4: Spell fix (Riana)

Signed-off-by: Raag Jadav <raag.jadav at intel.com>
Acked-by: Jani Nikula <jani.nikula at intel.com>
Reviewed-by: Riana Tauro <riana.tauro at intel.com>
Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_driver.c | 15 +++++++++++++++
 drivers/gpu/drm/i915/i915_reg.h    |  1 +
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index eb3fcc9e77a5..2251bedf9e3c 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -95,11 +95,13 @@
 #include "i915_memcpy.h"
 #include "i915_perf.h"
 #include "i915_query.h"
+#include "i915_reg.h"
 #include "i915_switcheroo.h"
 #include "i915_sysfs.h"
 #include "i915_utils.h"
 #include "i915_vgpu.h"
 #include "intel_clock_gating.h"
+#include "intel_cpu_info.h"
 #include "intel_gvt.h"
 #include "intel_memory_region.h"
 #include "intel_pci_config.h"
@@ -424,6 +426,18 @@ static int i915_set_dma_info(struct drm_i915_private *i915)
 	return ret;
 }
 
+/* Wa_14022698537:dg2 */
+static void i915_enable_g8(struct drm_i915_private *i915)
+{
+	if (IS_DG2(i915)) {
+		if (IS_DG2_D(i915) && !intel_match_g8_cpu())
+			return;
+
+		snb_pcode_write_p(&i915->uncore, PCODE_POWER_SETUP,
+				  POWER_SETUP_SUBCOMMAND_G8_ENABLE, 0, 0);
+	}
+}
+
 static int i915_pcode_init(struct drm_i915_private *i915)
 {
 	struct intel_gt *gt;
@@ -437,6 +451,7 @@ static int i915_pcode_init(struct drm_i915_private *i915)
 		}
 	}
 
+	i915_enable_g8(i915);
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f48b5c809cec..8dfa1f01500c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3578,6 +3578,7 @@
 #define	    POWER_SETUP_I1_WATTS		REG_BIT(31)
 #define	    POWER_SETUP_I1_SHIFT		6	/* 10.6 fixed point format */
 #define	    POWER_SETUP_I1_DATA_MASK		REG_GENMASK(15, 0)
+#define     POWER_SETUP_SUBCOMMAND_G8_ENABLE	0x6
 #define GEN12_PCODE_READ_SAGV_BLOCK_TIME_US	0x23
 #define   XEHP_PCODE_FREQUENCY_CONFIG		0x6e	/* pvc */
 /* XEHP_PCODE_FREQUENCY_CONFIG sub-commands (param1) */
-- 
2.34.1