On Fri, Apr 08, 2022 at 01:44:44PM +0100, Tvrtko Ursulin wrote:
On 05/04/2022 01:11, Lucas De Marchi wrote:
Since gen6 we use FPGA_DBG register to detect unclaimed MMIO registers.
This register is in the display engine IP and can only ever detect
unclaimed accesses to registers in this area. However sometimes there
are reports of this triggering for registers in other areas, which
should not be possible.
Right now we always warn after the read/write of registers going through
unclaimed_reg_debug(). However places using __raw_uncore_* may be
triggering the unclaimed access and those being later accounted to a
different register. Let's warn both before and after the read/write
with a slightly different message, so it's clear if the register
reported in the warning is actually the culprit.
Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
I see this triggering a lot on drm-tip today (TGL), is that expected?
[ 3.994907] i915 0000:00:02.0: [drm:intel_uncore_init_mmio [i915]] unclaimed mmio detected on uncore init, clearing
[ 4.392525] i915 0000:00:02.0: Unclaimed access detected before read from register 0x44408
[ 5.669929] i915 0000:00:02.0: Unclaimed access detected before write to register 0x50380
[ 6.652808] i915 0000:00:02.0: Unclaimed access detected before write to register 0x50380
[ 13.015978] i915 0000:00:02.0: Unclaimed access detected before write to register 0x50380
[ 16.876802] i915 0000:00:02.0: Unclaimed access detected before write to register 0x44404
[ 45.174395] i915 0000:00:02.0: Unclaimed access detected before write to register 0x44404
It continues at runtime as well:
[10265.010902] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10329.093078] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10354.060331] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10385.486480] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10408.910533] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10433.398443] i915 0000:00:02.0: Unclaimed access detected before write to register 0x1900ec
[10444.110593] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10468.302627] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10493.398727] i915 0000:00:02.0: Unclaimed access detected before write to register 0x1900ec
[10515.366845] i915 0000:00:02.0: Unclaimed access detected before read from register 0x44408
[10518.674046] i915 0000:00:02.0: Unclaimed access detected before read from register 0xc7204
[10529.934735] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10553.398808] i915 0000:00:02.0: Unclaimed access detected before write to register 0x1900ec
[10599.684455] i915 0000:00:02.0: Unclaimed access detected before read from register 0xc4008
[10602.898167] i915 0000:00:02.0: Unclaimed access detected before read from register 0xc7204
[10613.398909] i915 0000:00:02.0: Unclaimed access detected before write to register 0x1900ec
[10686.006783] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10711.906813] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10745.860538] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10771.812277] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10805.903058] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10831.927073] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10853.398958] i915 0000:00:02.0: Unclaimed access detected before write to register 0x1900ec
[10866.007084] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10879.378435] i915 0000:00:02.0: Unclaimed access detected before read from register 0xc7204
[10891.727120] i915 0000:00:02.0: Unclaimed access detected before write to register 0x190030
[10913.395161] i915 0000:00:02.0: Unclaimed access detected before write to register 0x1900ec
[10939.026480] i915 0000:00:02.0: Unclaimed access detected before read from register 0xc7204
[10964.626494] i915 0000:00:02.0: Unclaimed access detected before read from register 0xc7204
It don't think this machine had a problem with this before, or perhaps it was going undetected?
it was going undetected. However I have a patch to downgrade the first
message to debug, because we are clear not ready to enable the stricter
check. I will send it in a bit.
Lucas De Marchi
Regards,
Tvrtko
---
drivers/gpu/drm/i915/intel_uncore.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 8b9caaaacc21..df59ec88459e 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1502,11 +1502,10 @@ ilk_dummy_write(struct intel_uncore *uncore)
static void
__unclaimed_reg_debug(struct intel_uncore *uncore,
const i915_reg_t reg,
- const bool read,
- const bool before)
+ const bool read)
{
if (drm_WARN(&uncore->i915->drm,
- check_for_unclaimed_mmio(uncore) && !before,
+ check_for_unclaimed_mmio(uncore),
"Unclaimed %s register 0x%x\n",
read ? "read from" : "write to",
i915_mmio_reg_offset(reg)))
@@ -1514,6 +1513,20 @@ __unclaimed_reg_debug(struct intel_uncore *uncore,
uncore->i915->params.mmio_debug--;
}
+static void
+__unclaimed_previous_reg_debug(struct intel_uncore *uncore,
+ const i915_reg_t reg,
+ const bool read)
+{
+ if (drm_WARN(&uncore->i915->drm,
+ check_for_unclaimed_mmio(uncore),
+ "Unclaimed access detected before %s register 0x%x\n",
+ read ? "read from" : "write to",
+ i915_mmio_reg_offset(reg)))
+ /* Only report the first N failures */
+ uncore->i915->params.mmio_debug--;
+}
+
static inline void
unclaimed_reg_debug(struct intel_uncore *uncore,
const i915_reg_t reg,
@@ -1526,13 +1539,13 @@ unclaimed_reg_debug(struct intel_uncore *uncore,
/* interrupts are disabled and re-enabled around uncore->lock usage */
lockdep_assert_held(&uncore->lock);
- if (before)
+ if (before) {
spin_lock(&uncore->debug->lock);
-
- __unclaimed_reg_debug(uncore, reg, read, before);
-
- if (!before)
+ __unclaimed_previous_reg_debug(uncore, reg, read);
+ } else {
+ __unclaimed_reg_debug(uncore, reg, read);
spin_unlock(&uncore->debug->lock);
+ }
}
#define __vgpu_read(x) \
