From 1543e317f1da31b75942316931e8f491a8920811 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Thu, 04 Jan 2024 10:08:02 +0000
Subject: [PATCH] disable FB
---
kernel/drivers/gpu/drm/i915/gt/intel_reset.c | 34 ++++++++++++++++++++++++++++------
1 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/kernel/drivers/gpu/drm/i915/gt/intel_reset.c b/kernel/drivers/gpu/drm/i915/gt/intel_reset.c
index ac36b67..00b5912 100644
--- a/kernel/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/kernel/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -289,6 +289,7 @@
static int gen6_hw_domain_reset(struct intel_gt *gt, u32 hw_domain_mask)
{
struct intel_uncore *uncore = gt->uncore;
+ int loops = 2;
int err;
/*
@@ -296,18 +297,39 @@
* for fifo space for the write or forcewake the chip for
* the read
*/
- intel_uncore_write_fw(uncore, GEN6_GDRST, hw_domain_mask);
+ do {
+ intel_uncore_write_fw(uncore, GEN6_GDRST, hw_domain_mask);
- /* Wait for the device to ack the reset requests */
- err = __intel_wait_for_register_fw(uncore,
- GEN6_GDRST, hw_domain_mask, 0,
- 500, 0,
- NULL);
+ /*
+ * Wait for the device to ack the reset requests.
+ *
+ * On some platforms, e.g. Jasperlake, we see that the
+ * engine register state is not cleared until shortly after
+ * GDRST reports completion, causing a failure as we try
+ * to immediately resume while the internal state is still
+ * in flux. If we immediately repeat the reset, the second
+ * reset appears to serialise with the first, and since
+ * it is a no-op, the registers should retain their reset
+ * value. However, there is still a concern that upon
+ * leaving the second reset, the internal engine state
+ * is still in flux and not ready for resuming.
+ */
+ err = __intel_wait_for_register_fw(uncore, GEN6_GDRST,
+ hw_domain_mask, 0,
+ 2000, 0,
+ NULL);
+ } while (err == 0 && --loops);
if (err)
drm_dbg(>->i915->drm,
"Wait for 0x%08x engines reset failed\n",
hw_domain_mask);
+ /*
+ * As we have observed that the engine state is still volatile
+ * after GDRST is acked, impose a small delay to let everything settle.
+ */
+ udelay(50);
+
return err;
}
--
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