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Gustavo Sousa f14d81b710 drm/i915/cmtg: Disable the CMTG
The CMTG is a timing generator that runs in parallel with transcoders
timing generators and can be used as a reference for synchronization.

We have observed that we are inheriting from GOP a display configuration
with the CMTG enabled. Because our driver doesn't currently implement
any CMTG sequences, the CMTG ends up still enabled after our driver
takes over.

We need to make sure that the CMTG is not enabled if we are not going to
use it. For that, let's add a partial implementation in our driver that
only cares about disabling the CMTG if it was found enabled during
initial hardware readout. In the future, we can also implement sequences
for using the CMTG if that becomes a needed feature.

For now, we only deal with cases when it is possible to disable the CMTG
without requiring a modeset. For earlier display versions, we simply
skip if we find the CMTG enabled and we can't disable it without a
proper modeset. In the future, we need to properly handle that case.

v2:
 - DG2 does not have the CMTG. Update HAS_CMTG() accordingly.
 - Update logic to force disabling of CMTG only for initial commit.
v3:
 - Add missing changes for v2 that were staged but not committed.
v4:
 - Avoid if/else duplication in intel_cmtg_dump_state() by using "n/a"
   for CMTG B enabled/disabled string for platforms without it. (Jani)
 - Prefer intel_cmtg_readout_hw_state() over intel_cmtg_readout_state().
   (Jani)
 - Use display struct instead of i915 as first parameter for
   TRANS_DDI_FUNC_CTL2(). (Jani)
 - Fewer continuation lines in variable declaration/initialization for
   better readability. (Jani)
 - Coding style improvements. (Jani)
 - Use drm_dbg_kms() instead of drm_info() for logging the disabling
   of the CMTG.
 - Make struct intel_cmtg_state entirely private to intel_cmtg.c.
v5:
 - Do the disable sequence as part of the sanitization step after
   hardware readout instead of initial modeset commit. (Jani)
 - Adapt to commit 1513358246 ("drm/i915/display: convert global state
   to struct intel_display") by using a display struct instead of i915
   as argument for intel_atomic_global_obj_init().
v6:
 - Do not track CMTG state as a global state. (Ville)
 - Simplify the driver logic by only disabling the CMTG only on cases
   when a modeset is not required. (Ville)
v7:
 - Remove the call to drm_WARN_ON() when checking
   intel_cmtg_disable_requires_modeset() and use a FIXME in the comment
   instead.
 - Remove the !HAS_CMTG() guard from intel_cmtg_get_config(), which is
   static and its caller is already protected by that same condition.
 - Also take the opportunity to put some Bspec references in the commit
   trailers section.
v8:
 - Use HAS_TRANSCODER() instead of intel_crtc_for_pipe(). (Ville)
 - Ensure transcoder power well is enabled before reading
   TRANS_DDI_FUNC_CTL2. (Ville)

Bspec: 68915, 49262
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250124173956.46534-1-gustavo.sousa@intel.com
2025-01-27 14:06:23 -03:00
arch drm-misc-next for 6.14: 2024-12-20 08:24:34 +10:00
block block: Fix potential deadlock while freezing queue and acquiring sysfs_lock 2024-12-13 10:51:58 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: rsassa-pkcs1 - Copy source data for SG list 2024-12-10 13:34:05 +08:00
Documentation drm-misc-next for 6.14: 2024-12-20 08:24:34 +10:00
drivers drm/i915/cmtg: Disable the CMTG 2025-01-27 14:06:23 -03:00
fs First batch of EFI fixes for v6.13 2024-12-15 15:33:41 -08:00
include drm/i915/display: Add MTL subplatforms definition 2025-01-16 15:05:14 -08:00
init - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
io_uring io_uring/rsrc: don't put/free empty buffers 2024-12-12 08:01:52 -07:00
ipc - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
kernel - Prevent incorrect dequeueing of the deadline dlserver helper task and fix 2024-12-15 09:38:03 -08:00
lib drm-misc-next for 6.14: 2024-12-20 08:24:34 +10:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm slab fixes for 6.13-rc3 2024-12-13 09:43:50 -08:00
net BPF fixes: 2024-12-14 12:58:14 -08:00
rust rust: kbuild: set bindgen's Rust target version 2024-12-10 01:06:10 +01:00
samples BPF fixes: 2024-12-06 15:07:48 -08:00
scripts A single fix for a docs-build regression caused by the EXPORT_SYMBOL_NS() 2024-12-13 09:46:02 -08:00
security Including fixes from can and netfilter. 2024-12-05 10:25:06 -08:00
sound ASoC: Fixes for v6.13 2024-12-12 14:49:35 +01:00
tools BPF fixes: 2024-12-14 12:58:14 -08:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt VFIO updates for v6.13 2024-11-27 12:57:03 -08:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: enable Clippy's check-private-items 2024-10-07 21:39:57 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.13 2024-11-30 13:41:50 -08:00
.mailmap media updates for v6.13-rc1 2024-11-20 14:01:15 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS cgroup: Changes for v6.13 2024-11-20 09:54:49 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: switch my mail address for GVT driver 2025-01-09 16:08:43 -05:00
Makefile Linux 6.13-rc3 2024-12-15 15:58:23 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.