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Hersen Wu 6513104ba4 drm/amd/display: dsc mst 2 4K displays go dark with 2 lane HBR3
[Why]
call stack of amdgpu dsc mst pbn, slot num calculation is as below:
-compute_bpp_x16_from_target_bandwidth
-decide_dsc_target_bpp_x16
-setup_dsc_config
-dc_dsc_compute_bandwidth_range
-compute_mst_dsc_configs_for_link
-compute_mst_dsc_configs_for_state

from pbn -> dsc target bpp_x16

bpp_x16 is calulated by compute_bpp_x16_from_target_bandwidth.
Beside pixel clock and bpp, num_slices_h and bpp_increment_div
will also affect bpp_x16.

from dsc target bpp_x16 -> pbn

within dm_update_mst_vcpi_slots_for_dsc,
pbn = drm_dp_calc_pbn_mode(clock, bpp_x16, true);

drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
{
  return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006),
            8 * 54 * 1000 * 1000);
}

bpp / 16 trunc digits after decimal point. This will cause calculation
delta. drm_dp_calc_pbn_mode does not have other informations,
like num_slices_h, bpp_increment_div. therefore, it does not do revese
calcuation properly from bpp_x16 to pbn.

pbn from drm_dp_calc_pbn_mode is less than pbn from
compute_mst_dsc_configs_for_state. This cause not enough mst slot
allocated to display. display could not visually light up.

[How]
pass pbn from compute_mst_dsc_configs_for_state to
dm_update_mst_vcpi_slots_for_dsc

Cc: stable@vger.kernel.org

Reviewed-by: Scott Foster <Scott.Foster@amd.com>
Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Hersen Wu <hersenwu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
History 2021-09-14 15:57:10 -04:00
arch Bus: Make remove callback return void tag 2021-08-11 08:47:08 +10:00
block block-5.14-2021-07-08 2021-07-09 12:05:33 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-07-09 11:00:44 -07:00
Documentation Merge tag 'drm-msm-next-2021-08-12' of https://gitlab.freedesktop.org/drm/msm into drm-next 2021-08-17 10:53:52 +10:00
drivers drm/amd/display: dsc mst 2 4K displays go dark with 2 lane HBR3 2021-09-14 15:57:10 -04:00
fs 5 cifs/smb3 fixes, including a DFS failover fix, 2 fallocate fixes, and 2 trivial coverity cleanups 2021-07-24 17:26:47 -07:00
include drm/tegra: Changes for v5.15-rc1 2021-08-26 13:05:19 +10:00
init Revert "mm/slub: use stackdepot to save stack trace in objects" 2021-07-17 13:27:00 -07:00
ipc Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
kernel smpboot: fix duplicate and misplaced inlining directive 2021-07-25 11:06:37 -07:00
lib lib/test_hmm: remove set but unused page variable 2021-07-15 10:13:49 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: fix the deadlock in finish_fault() 2021-07-23 17:43:28 -07:00
net net: sched: cls_api: Fix the the wrong parameter 2021-07-22 00:48:03 -07:00
samples Networking fixes for 5.14-rc2, including fixes from bpf and netfilter. 2021-07-14 09:24:32 -07:00
scripts Kbuild fixes for v5.14 2021-07-18 11:10:30 -07:00
security asm-generic/unaligned: Unify asm/unaligned.h around struct helper 2021-07-02 12:43:40 -07:00
sound Bus: Make remove callback return void tag 2021-08-11 08:47:08 +10:00
tools selftest: use mmap instead of posix_memalign to allocate memory 2021-07-23 17:43:28 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt * Allow again loading KVM on 32-bit non-PAE builds 2021-07-15 11:56:07 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap m68k updates for v5.14 2021-06-28 14:01:03 -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 Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
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 Merge tag 'amd-drm-next-5.15-2021-07-29' of https://gitlab.freedesktop.org/agd5f/linux into drm-next 2021-07-30 16:48:35 +10:00
Makefile Linux 5.14-rc3 2021-07-25 15:35:14 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.