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Umesh Nerlige Ramappa bc7ed4d308 drm/i915/perf: Apply Wa_18013179988
OA reports in the OA buffer contain an OA timestamp field that helps
user calculate delta between 2 OA reports. The calculation relies on the
CS timestamp frequency to convert the timestamp value to nanoseconds.
The CS timestamp frequency is a function of the CTC_SHIFT value in
RPM_CONFIG0.

In DG2, OA unit assumes that the CTC_SHIFT is 3, instead of using the
actual value from RPM_CONFIG0. At the user level, this results in an
error in calculating delta between 2 OA reports since the OA timestamp
is not shifted in the same manner as CS timestamp. Also the periodicity
of the reports is different from what the user configured because of
mismatch in the CS and OA frequencies.

The issue also affects MI_REPORT_PERF_COUNT command.

To resolve this, return actual OA timestamp frequency to the user in
i915_getparam_ioctl, so that user can calculate the right OA exponent as
well as interpret the reports correctly.

MR: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18893

v2:
- Use REG_FIELD_GET (Ashutosh)
- Update commit msg

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026222102.5526-13-umesh.nerlige.ramappa@intel.com
2022-10-27 12:36:53 -07:00
arch Misc irqchip fixes: LoongArch driver fixes and a Hyper-V IOMMU fix. 2022-08-21 15:09:55 -07:00
block block-6.0-2022-08-19 2022-08-20 10:17:05 -07:00
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crypto
Documentation drm/i915/hwmon: Extend power/energy for XEHPSDV 2022-10-17 14:57:50 +05:30
drivers drm/i915/perf: Apply Wa_18013179988 2022-10-27 12:36:53 -07:00
fs 5 cifs/smb3 fixes, one for stable 2022-08-21 10:21:16 -07:00
include drm/i915/perf: Apply Wa_18013179988 2022-10-27 12:36:53 -07:00
init asm goto: eradicate CC_HAS_ASM_GOTO 2022-08-21 10:06:28 -07:00
io_uring io_uring/net: use right helpers for async_data 2022-08-18 07:27:20 -06:00
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kernel Various fixes for tracing: 2022-08-21 14:49:42 -07:00
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security hardening fixes for v6.0-rc2 2022-08-19 13:56:14 -07:00
sound sound fixes for 6.0-rc2 2022-08-19 09:46:11 -07:00
tools asm goto: eradicate CC_HAS_ASM_GOTO 2022-08-21 10:06:28 -07:00
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virt KVM: Drop unnecessary initialization of "ops" in kvm_ioctl_create_device() 2022-08-19 04:05:43 -04:00
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MAINTAINERS drm/i915/hwmon: Add HWMON current voltage support 2022-10-17 14:50:14 +05:30
Makefile Linux 6.0-rc2 2022-08-21 17:32:54 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.