[PATCH v2 2/2] drm/i915/guc: Allow for very slow GuC loading

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

A failure to load the GuC is occasionally observed where the GuC log
actually showed that the GuC had loaded just fine. The implication
being that the load just took ever so slightly longer than the 200ms
timeout. Given that the actual time should be tens of milliseconds at
the slowest, this should never happen. So far the issue has generally
been caused by a bad IFWI resulting in low frequencies during boot
(depsite the KMD requesting max frequency). However, the issue seems
to happen more often than one would like.

So a) increase the timeout so that the user still gets a working
system even in the case of slow load. And b) report the frequency
during the load to see if that is the case of the slow down.

v2: Reduce timeout in non-debug builds, add references (Daniele)

References: https://gitlab.freedesktop.org/drm/intel/-/issues/7931
References: https://gitlab.freedesktop.org/drm/intel/-/issues/8060
References: https://gitlab.freedesktop.org/drm/intel/-/issues/8083
References: https://gitlab.freedesktop.org/drm/intel/-/issues/8136
References: https://gitlab.freedesktop.org/drm/intel/-/issues/8137
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c | 50 +++++++++++++++++++++--
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
index 0b49d84a8a9c2..6fda3aec5c66a 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
@@ -12,6 +12,7 @@
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_mcr.h"
 #include "gt/intel_gt_regs.h"
+#include "gt/intel_rps.h"
 #include "intel_guc_fw.h"
 #include "intel_guc_print.h"
 #include "i915_drv.h"
@@ -135,13 +136,29 @@ static inline bool guc_load_done(struct intel_uncore *uncore, u32 *status, bool
 	return false;
 }
 
+/*
+ * Use a longer timeout for debug builds so that problems can be detected
+ * and analysed. But a shorter timeout for releases so that user's don't
+ * wait forever to find out there is a problem. Note that the only reason
+ * an end user should hit the timeout is in case of extreme thermal throttling.
+ * And a system that is that hot during boot is probably dead anyway!
+ */
+#if defined(CONFIG_DRM_I915_DEBUG_GEM)
+#define GUC_LOAD_RETRY_LIMIT	20
+#else
+#define GUC_LOAD_RETRY_LIMIT	3
+#endif
+
 static int guc_wait_ucode(struct intel_guc *guc)
 {
 	struct intel_gt *gt = guc_to_gt(guc);
 	struct intel_uncore *uncore = gt->uncore;
+	ktime_t before, after, delta;
 	bool success;
 	u32 status;
-	int ret;
+	int ret, count;
+	u64 delta_ms;
+	u32 before_freq;
 
 	/*
 	 * Wait for the GuC to start up.
@@ -159,13 +176,32 @@ static int guc_wait_ucode(struct intel_guc *guc)
 	 * issues to be resolved. In the meantime bump the timeout to
 	 * 200ms. Even at slowest clock, this should be sufficient. And
 	 * in the working case, a larger timeout makes no difference.
+	 *
+	 * IFWI updates have also been seen to cause sporadic failures due to
+	 * the requested frequency not being granted and thus the firmware
+	 * load is attempted at minimum frequency. That can lead to load times
+	 * in the seconds range. However, there is a limit on how long an
+	 * individual wait_for() can wait. So wrap it in a loop.
 	 */
-	ret = wait_for(guc_load_done(uncore, &status, &success), 200);
+	before_freq = intel_rps_read_actual_frequency(&uncore->gt->rps);
+	before = ktime_get();
+	for (count = 0; count < GUC_LOAD_RETRY_LIMIT; count++) {
+		ret = wait_for(guc_load_done(uncore, &status, &success), 1000);
+		if (!ret || !success)
+			break;
+
+		guc_dbg(guc, "load still in progress, count = %d, freq = %dMHz\n",
+			count, intel_rps_read_actual_frequency(&uncore->gt->rps));
+	}
+	after = ktime_get();
+	delta = ktime_sub(after, before);
+	delta_ms = ktime_to_ms(delta);
 	if (ret || !success) {
 		u32 ukernel = REG_FIELD_GET(GS_UKERNEL_MASK, status);
 		u32 bootrom = REG_FIELD_GET(GS_BOOTROM_MASK, status);
 
-		guc_info(guc, "load failed: status = 0x%08X, ret = %d\n", status, ret);
+		guc_info(guc, "load failed: status = 0x%08X, time = %lldms, freq = %dMHz, ret = %d\n",
+			 status, delta_ms, intel_rps_read_actual_frequency(&uncore->gt->rps), ret);
 		guc_info(guc, "load failed: status: Reset = %d, BootROM = 0x%02X, UKernel = 0x%02X, MIA = 0x%02X, Auth = 0x%02X\n",
 			 REG_FIELD_GET(GS_MIA_IN_RESET, status),
 			 bootrom, ukernel,
@@ -206,6 +242,14 @@ static int guc_wait_ucode(struct intel_guc *guc)
 		/* Uncommon/unexpected error, see earlier status code print for details */
 		if (ret == 0)
 			ret = -ENXIO;
+	} else if (delta_ms > 200) {
+		guc_warn(guc, "excessive init time: %lldms! [freq = %dMHz, before = %dMHz, status = 0x%08X, count = %d, ret = %d]\n",
+			 delta_ms, intel_rps_read_actual_frequency(&uncore->gt->rps),
+			 before_freq, status, count, ret);
+	} else {
+		guc_dbg(guc, "init took %lldms, freq = %dMHz, before = %dMHz, status = 0x%08X, count = %d, ret = %d\n",
+			delta_ms, intel_rps_read_actual_frequency(&uncore->gt->rps),
+			before_freq, status, count, ret);
 	}
 
 	return ret;
-- 
2.39.1