[igt-dev] [PATCH i-g-t v12 6/6] tests/i915/i915_pm_dc:Skip the DC6 test if it doesn't support PC8+

[Anshuman Gupta <anshuman.gupta@intel.com>]

This patch validates if platform has limited Package C state
residencies from BIOS, if that true skip the DC6 IGT test.
As DC6 required platform to enter PC8 state.

Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
---
 tests/i915/i915_pm_dc.c | 55 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/tests/i915/i915_pm_dc.c b/tests/i915/i915_pm_dc.c
index ba891d85..e6e396f6 100644
--- a/tests/i915/i915_pm_dc.c
+++ b/tests/i915/i915_pm_dc.c
@@ -26,19 +26,35 @@
 #include "igt_sysfs.h"
 #include "igt_psr.h"
 #include <errno.h>
+#include <fcntl.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 #include "intel_bufmgr.h"
 #include "intel_io.h"
 #include "limits.h"
+#include "igt_kmod.h"
 
 /* DC State Flags */
 #define CHECK_DC5	1
 #define CHECK_DC6	2
 
+#define MSR_PKG_CST_CONFIG_CONTROL	0xE2
+/*
+ * Below PKG CST limit mask and PC8 bits are meant for
+ * HSW,BDW SKL,ICL and Goldmont Microarch and future platforms.
+ * Refer IA S/W developers manual vol3c part3 chapter:35
+ */
+#define  PKG_CST_LIMIT_MASK		0xF
+#define  PKG_CST_LIMIT_C8		0x6
+
+#define MSR_PC8_RES	0x630
+#define MSR_PC9_RES	0x631
+#define MSR_PC10_RES	0x632
+
 typedef struct {
 	int drm_fd;
+	int msr_fd;
 	int debugfs_fd;
 	uint32_t devid;
 	igt_display_t display;
@@ -52,6 +68,34 @@ typedef struct {
 bool dc_state_wait_entry(int drm_fd, int dc_flag, int prev_dc_count);
 void check_dc_counter(int drm_fd, int dc_flag, uint32_t prev_dc_count);
 
+/* If the read fails, then the machine doesn't support PC8+ residencies. */
+static bool supports_pc8_plus_residencies(data_t *data)
+{
+	int rc;
+	uint64_t val;
+	int msr_fd = data->msr_fd;
+
+	rc = pread(msr_fd, &val, sizeof(uint64_t), MSR_PC8_RES);
+	if (rc != sizeof(val))
+		return false;
+	rc = pread(msr_fd, &val, sizeof(uint64_t), MSR_PC9_RES);
+	if (rc != sizeof(val))
+		return false;
+	rc = pread(msr_fd, &val, sizeof(uint64_t), MSR_PC10_RES);
+	if (rc != sizeof(val))
+		return false;
+
+	rc = pread(msr_fd, &val, sizeof(uint64_t), MSR_PKG_CST_CONFIG_CONTROL);
+	if (rc != sizeof(val))
+		return false;
+	if ((val & PKG_CST_LIMIT_MASK) < PKG_CST_LIMIT_C8) {
+		igt_info("PKG C-states limited below PC8 by the BIOS\n");
+		return false;
+	}
+
+	return true;
+}
+
 static void setup_output(data_t *data)
 {
 	igt_display_t *display = &data->display;
@@ -249,6 +293,12 @@ int main(int argc, char *argv[])
 		igt_require(has_runtime_pm);
 		igt_require(igt_pm_dmc_loaded(data.debugfs_fd));
 		igt_display_require(&data.display, data.drm_fd);
+		/* Make sure our Kernel supports MSR and the module is loaded */
+		igt_require(igt_kmod_load("msr", NULL) == 0);
+
+		data.msr_fd = open("/dev/cpu/0/msr", O_RDONLY);
+		igt_assert_f(data.msr_fd >= 0,
+			     "Can't open /dev/cpu/0/msr.\n");
 	}
 
 	igt_subtest("dc5-psr") {
@@ -264,6 +314,8 @@ int main(int argc, char *argv[])
 		psr_enable(data.debugfs_fd, data.op_psr_mode);
 		igt_require_f(edp_psr_sink_support(&data),
 			      "Sink does not support PSR\n");
+		igt_require_f(supports_pc8_plus_residencies(&data),
+			      "PC8+ residencies not supported\n");
 		test_dc_state_psr(&data, CHECK_DC6);
 	}
 
@@ -273,12 +325,15 @@ int main(int argc, char *argv[])
 	}
 
 	igt_subtest("dc6-dpms") {
+		igt_require_f(supports_pc8_plus_residencies(&data),
+			      "PC8+ residencies not supported\n");
 		setup_dc_dpms(&data);
 		test_dc_state_dpms(&data, CHECK_DC6);
 	}
 
 	igt_fixture {
 		close(data.debugfs_fd);
+		close(data.msr_fd);
 		display_fini(&data);
 	}
 
-- 
2.21.0

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