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Lionel Landwerlin 059a0beb48 drm/i915/perf: workaround register corruption in OATAILPTR
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
2020-11-19 15:46:29 +02:00
Documentation Merge tag 'drm-intel-next-queued-2020-11-03' of git://anongit.freedesktop.org/drm/drm-intel into drm-next 2020-11-04 12:17:34 +10:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
arch Three fixes all related to #DB: 2020-11-01 11:21:26 -08:00
block blk-mq: mark flush request as IDLE in flush_end_io() 2020-10-30 08:33:49 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
drivers drm/i915/perf: workaround register corruption in OATAILPTR 2020-11-19 15:46:29 +02:00
fs Driver core / Documentation fixes for 5.10-rc2 2020-11-01 09:59:13 -08:00
include drm/i915: Sort EHL/JSL PCI IDs 2020-11-06 14:09:30 +02:00
init linux-kselftest-kunit-5.10-rc1 2020-10-18 14:45:59 -07:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel A few fixes for timers/timekeeping: 2020-11-01 11:13:45 -08:00
lib Driver core / Documentation fixes for 5.10-rc2 2020-11-01 09:59:13 -08:00
mm mm/process_vm_access: Add missing #include <linux/compat.h> 2020-10-27 12:41:29 -07:00
net flexible-array member conversion patches for 5.10-rc2 2020-10-31 14:31:28 -07:00
samples misc: mic: remove the MIC drivers 2020-10-28 19:12:03 +01:00
scripts scripts: get_abi.pl: assume ReST format by default 2020-10-30 13:16:03 +01:00
security ima: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
sound ARM: SoC platform updates 2020-10-24 10:33:08 -07:00
tools ARM: 2020-11-01 09:43:32 -08:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt kvm: x86/mmu: Support dirty logging for the TDP MMU 2020-10-23 03:42:13 -04:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: jarkko.sakkinen@linux.intel.com -> jarkko@kernel.org 2020-10-16 11:11:19 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Sangbeom Kim to credits 2020-10-26 10:11:18 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS drm-misc-next for 5.11: 2020-11-04 11:49:10 +10:00
Makefile Linux 5.10-rc2 2020-11-01 14:43:51 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.