Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-16 00:52:01 +00:00
Code Issues Packages Projects Releases Wiki Activity

drm/i915/perf: workaround register corruption in OATAILPTR

Browse Source 
After having written the entire OA buffer with reports, the HW will
write again at the beginning of the OA buffer. It'll indicate it by
setting the WRAP bits in the OASTATUS register.

When a wrap happens and that at the end of the read vfunc we write the
OASTATUS register back to clear the REPORT_LOST bit, we sometimes see
that the OATAILPTR register is reset to a previous position on Gen8/9
(apparently not the case on Gen11+). This leads the next call to the
read vfunc to process reports we've already read. Because we've marked
those as read by clearing the reason & timestamp dwords, they're
discarded and a "Skipping spurious, invalid OA report" message is
emitted.

The workaround to avoid this OATAILPTR value reset seems to be to set
the wrap bits when writing back OASTATUS.

This change has no impact on userspace, it only avoids a bunch of
DRM_NOTE("Skipping spurious, invalid OA report\n") messages.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: 19f81df285 ("drm/i915/perf: Add OA unit support for Gen 8+")
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201117130124.829979-1-lionel.g.landwerlin@intel.com
This commit is contained in:
Lionel Landwerlin 2020-11-17 15:01:24 +02:00
parent 919c2299a8
commit 059a0beb48
2 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/gpu/drm/i915/i915_perf.c
View File

@ -909,8 +909,13 @@ static int gen8_oa_read(struct i915_perf_stream *stream,
DRM_I915_PERF_RECORD_OA_REPORT_LOST);
if (ret)
return ret;
intel_uncore_write(uncore, oastatus_reg,
oastatus & ~GEN8_OASTATUS_REPORT_LOST);
intel_uncore_rmw(uncore, oastatus_reg,
GEN8_OASTATUS_COUNTER_OVERFLOW |
GEN8_OASTATUS_REPORT_LOST,
IS_GEN_RANGE(uncore->i915, 8, 10) ?
(GEN8_OASTATUS_HEAD_POINTER_WRAP |
GEN8_OASTATUS_TAIL_POINTER_WRAP) : 0);
}
return gen8_append_oa_reports(stream, buf, count, offset);

2
drivers/gpu/drm/i915/i915_reg.h
View File

@ -679,6 +679,8 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
#define GEN7_OASTATUS2_MEM_SELECT_GGTT (1 << 0) /* 0: PPGTT, 1: GGTT */
#define GEN8_OASTATUS _MMIO(0x2b08)
#define GEN8_OASTATUS_TAIL_POINTER_WRAP (1 << 17)
#define GEN8_OASTATUS_HEAD_POINTER_WRAP (1 << 16)
#define GEN8_OASTATUS_OVERRUN_STATUS (1 << 3)
#define GEN8_OASTATUS_COUNTER_OVERFLOW (1 << 2)
#define GEN8_OASTATUS_OABUFFER_OVERFLOW (1 << 1)