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Tvrtko Ursulin 6c2b0103ad drm/i915: Fix and improve MCR selection logic
A couple issues were present in this code:

1.
fls() usage was incorrect causing off by one in subslice mask lookup,
which in other words means subslice mask of all zeroes is always used
(subslice mask of a slice which is not present, or even out of bounds
array access), rendering the checks in wa_init_mcr either futile or
random.

2.
Condition in WARN_ON was not correct. It is doing a bitwise and operation
between a positive (present subslices) and negative mask (disabled L3
banks).

This means that with corrected fls() usage the assert would always
incorrectly fail.

We could fix this by inverting the fuse bits in the check, but instead do
one better and improve the code so it not only asserts, but finds the
first common index between the two masks and only warns if no such index
can be found.

v2:
 * Simplify check for logic and redability.
 * Improve commentary explaining what is really happening ie. what the
   assert is really trying to check and why.

v3:
 * Find first common index instead of just asserting.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: fe864b76c2 ("drm/i915: Implement WaProgramMgsrForL3BankSpecificMmioReads")
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> # v1
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190717180624.20354-4-tvrtko.ursulin@linux.intel.com
2019-07-19 15:35:19 +01:00
arch x86/gpu: add TGL stolen memory support 2019-07-17 14:46:21 -07:00
block blk-mq: remove WARN_ON(!q->elevator) from blk_mq_sched_free_requests 2019-06-13 03:05:58 -06:00
certs
crypto SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
Documentation Merge tag 'drm-msm-next-2019-06-25' of https://gitlab.freedesktop.org/drm/msm into drm-next 2019-06-28 10:16:40 +10:00
drivers drm/i915: Fix and improve MCR selection logic 2019-07-19 15:35:19 +01:00
fs Fix rounding error in gfs2_iomap_page_prepare 2019-06-14 17:27:12 -10:00
include drm/i915: Drop extern qualifiers from header function prototypes 2019-07-12 13:04:54 +01:00
init Char/Misc driver fixes for 5.2-rc4 2019-06-08 12:50:36 -07:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-16 07:22:56 -10:00
lib lib/genalloc: introduce chunk owners 2019-06-13 17:34:56 -10:00
LICENSES
mm Merge branch 'vmwgfx-next' of git://people.freedesktop.org/~thomash/linux into drm-next 2019-06-21 12:18:16 +10:00
net SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
samples SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
scripts scripts/decode_stacktrace.sh: prefix addr2line with $CROSS_COMPILE 2019-06-13 17:34:56 -10:00
security Smack: Restore the smackfsdef mount option and add missing prefixes 2019-06-14 14:25:04 -10:00
sound sound fixes for 5.2-rc5 2019-06-14 05:37:06 -10:00
tools mm/devm_memremap_pages: fix final page put race 2019-06-13 17:34:56 -10:00
usr
virt treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS MAINTAINERS: Farewell Martin Schwidefsky 2019-05-31 10:14:11 +02:00
Kbuild
Kconfig
MAINTAINERS Merge branch 'vmwgfx-next' of git://people.freedesktop.org/~thomash/linux into drm-next 2019-06-21 12:18:16 +10:00
Makefile Linux 5.2-rc5 2019-06-16 08:49:45 -10:00
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.