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Imre Deak 4e0837a8d0 drm/i915/dp_mst: Account for FEC and DSC overhead during BW allocation
Atm, the BW allocated for an MST stream doesn't take into account the
DSC control symbol (EOC) and data alignment overhead on the local (first
downstream) MST link (reflected by the data M/N/TU values) and - besides
the above overheads - the FEC symbol overhead on 8b/10b remote
(after a downstream branch device) MST links.

In addition the FEC overhead used on the local link is a fixed amount,
which only applies to certain modes, but not enough for all modes; add a
code comment clarifying this.

Fix the above by calculating the data M/N values with the total BW
overhead (not including the SSC overhead, since this isn't enabled by
the source device) and using this the PBN and TU values for the local
link and PBN for remote links (including SSC, since this is mandatory
for links after downstream branch devices).

For now keep the current fixed FEC overhead as a minimum, since this is
what bspec requires for audio functionality.

Calculate the effective link BW in a clearer way, applying the channel
coding efficiency based on the coding type. The calculation was correct
for 8b/10b, but not for 128b/132b links; this patch leaves the behavior
for this unchanged, leaving the fix for a follow-up.

v2:
- Fix TU size programmed to the HW, making it match the payload size
  programmed to the payload table.
v3:
- Add code comment about the connection between the payload's size in
  the payload table and the corresponding PBN value. (Ville)
- Add WARN_ON(remote_m_n.tu < dp_m_n.tu). (Ville)
- Add code comment about factors not accounted for by the BW
  calculation in intel_dp_mst_mode_valid_ctx() (and compute config).
  (Ville)
- Simplify calculation of PBN to remote_m_n.tu * mst_state->pbn_div.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> (v1)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231107001505.3370108-2-imre.deak@intel.com
2023-11-08 17:22:13 +02:00
arch Misc fixes: 2023-09-17 11:13:37 -07:00
block blk-mq: fix tags UAF when shrinking q->nr_hw_queues 2023-09-11 16:17:34 -06:00
certs
crypto
Documentation Merge drm/drm-next into drm-intel-next 2023-10-04 18:06:27 +03:00
drivers drm/i915/dp_mst: Account for FEC and DSC overhead during BW allocation 2023-11-08 17:22:13 +02:00
fs stat: remove no-longer-used helper macros 2023-09-17 10:46:12 -07:00
include drm/dp: Add helpers to calculate the link BW overhead 2023-11-08 17:22:10 +02:00
init
io_uring io_uring/net: fix iter retargeting for selected buf 2023-09-14 10:12:55 -06:00
ipc
kernel Fix a performance regression on large SMT systems, an Intel SMT4 2023-09-17 11:10:23 -07:00
lib linux-kselftest-kunit-6.6-rc2 2023-09-12 09:05:49 -07:00
LICENSES
mm vm: fix move_vma() memory accounting being off 2023-09-16 15:23:31 -07:00
net kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg(). 2023-09-14 10:43:51 +02:00
rust
samples
scripts Kbuild fixes for v6.6 2023-09-16 15:27:00 -07:00
security selinux: fix handling of empty opts in selinux_fs_context_submount() 2023-09-12 17:31:08 -04:00
sound sound fixes for 6.6-rc1 2023-09-08 13:07:50 -07:00
tools Fix a cold functions related false-positive objtool warning 2023-09-17 10:59:37 -07:00
usr
virt ARM: 2023-09-07 13:52:20 -07:00
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MAINTAINERS Merge tag 'drm-misc-next-2023-09-27' of git://anongit.freedesktop.org/drm/drm-misc into drm-next 2023-09-29 08:27:15 +10:00
Makefile Linux 6.6-rc2 2023-09-17 14:40:24 -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.