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Douglas Anderson 9e15123eca drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset 
In commit 7d8e9a9050 ("drm/msm/dsi: move DSI host powerup to modeset
time"), we moved powering up DSI hosts to modeset time. This wasn't
because it was an elegant design, but there were no better options.

That commit actually ended up breaking ps8640, and thus was born
commit ec7981e6c6 ("drm/msm/dsi: don't powerup at modeset time for
parade-ps8640") as a temporary hack to un-break ps8640 by moving it to
the old way of doing things. It turns out that ps8640 _really_ doesn't
like its pre_enable() function to be called after
dsi_mgr_bridge_power_on(). Specifically (from experimentation, not
because I have any inside knowledge), it looks like the assertion of
"RST#" in the ps8640 runtime resume handler seems like it's not
allowed to happen after dsi_mgr_bridge_power_on()

Recently, Dave Stevenson's series landed allowing bridges some control
over pre_enable ordering. The meaty commit for our purposes is
commit 4fb912e5e1 ("drm/bridge: Introduce pre_enable_prev_first to
alter bridge init order"). As documented by that series, if a bridge
doesn't set "pre_enable_prev_first" then we should use the old ordering.

Now that we have the commit ("drm/bridge: tc358762: Set
pre_enable_prev_first") we can go back to the old ordering, which also
allows us to remove the ps8640 special case.

One last note is that even without reverting commit 7d8e9a9050
("drm/msm/dsi: move DSI host powerup to modeset time"), if you _just_
revert the ps8640 special case and try it out then it doesn't seem to
fail anymore. I spent time bisecting / debugging this and it turns out
to be mostly luck, so we still want this patch to make sure it's
solid. Specifically the reason it sorta works these days is because
we implemented wait_hpd_asserted() in ps8640 now, plus the magic of
"pm_runtime" autosuspend. The fact that we have wait_hpd_asserted()
implemented means that we actually power the bridge chip up just a wee
bit earlier and then the bridge happens to stay on because of
autosuspend and thus ends up powered before dsi_mgr_bridge_power_on().

Cc: Dave Stevenson <dave.stevenson@raspberrypi.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/521058/
Link: https://lore.kernel.org/r/20230131141756.RFT.v2.2.I4cfeab9d0e07e98ead23dd0736ab4461e6c69002@changeid
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
 		2023-05-21 02:18:18 +03:00
Documentation dt-bindings: display/msm: dsi-controller-main: Document qcom, master-dsi and qcom, sync-dual-dsi 2023-04-28 12:06:20 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch - Disable XSAVES on AMD Zen1 and Zen2 machines due to an erratum. No 2023-03-12 09:12:03 -07:00
block block, bfq: fix uaf for 'stable_merge_bfqq' 2023-03-08 07:34:50 -07:00
certs Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
crypto Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
drivers drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset 2023-05-21 02:18:18 +03:00
fs Fixes for 6.3-rc1: 2023-03-12 09:47:08 -07:00
include drm/msm: Rename drm_msm_gem_submit_reloc::or in C++ code 2023-04-06 20:29:39 +03:00
init Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
io_uring io_uring: silence variable ‘prev’ set but not used warning 2023-03-09 10:10:58 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel kernel.fork.v6.3-rc2 2023-03-12 09:04:28 -07:00
lib cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
mm mm: avoid gcc complaint about pointer casting 2023-03-04 14:03:27 -08:00
net wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext" 2023-03-12 16:21:59 -07:00
rust Rust fixes for 6.3-rc1 2023-03-03 14:51:15 -08:00
samples LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
scripts Remove Intel compiler support 2023-03-05 10:49:37 -08:00
security capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
sound sound fixes for 6.3-rc1 2023-03-04 10:53:59 -08:00
tools kernel.fork.v6.3-rc2 2023-03-12 09:04:28 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM/riscv changes for 6.3 2023-02-15 12:33:28 -05:00
.clang-format cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
.cocciconfig
…
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore .gitignore: ignore *.cover and *.mbx 2023-02-05 18:51:22 +09:00
.mailmap drm fixes for 6.3-rc2 2023-03-10 08:57:46 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING
…
CREDITS There is no particular theme here - mainly quick hits all over the tree. 2023-02-23 17:55:40 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
…
MAINTAINERS MAINTAINERS: Update the URI for MSM DRM bugs 2023-03-20 13:58:44 -07:00
Makefile Linux 6.3-rc2 2023-03-12 16:36:44 -07:00
README
…

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.