b896898c73
The WA specifies that we need to toggle a SDE chicken bit on and then
off as the final step in preparation for s0ix entry.
Bspec: 33450
Bspec: 8402
However, something is happening after we toggle the bit that causes
the WA to be invalidated. This makes dispcnlunit1_cp_xosc_clkreq
active being already in s0ix state i.e SLP_S0 counter incremented.
Tweaking the Wa_14010685332 by setting the bit on suspend and clearing
it on resume turns down the dispcnlunit1_cp_xosc_clkreq.
B.Spec has Documented this tweaked sequence of WA as an alternative.
Let keep this tweaked WA for Gen11 platforms and keep untweaked WA for
other platforms which never observed this issue.
v2 (MattR):
- Change the comment on the workaround to give PCH names rather than
platform names. Although the bspec is setup to list workarounds by
platform, the hardware team has confirmed that the actual issue being
worked around here is something that was introduced back in the
Cannon Lake PCH and carried forward to subsequent PCH's.
- Extend the untweaked version of the workaround to include PCH_CNP as
well. Note that since PCH_CNP is used to represent CMP, this will
apply on CML and some variants of RKL too.
- Cap the untweaked version of the workaround so that it won't apply to
"fake" PCH's (i.e., DG1). The issue we're working around really is
an issue in the PCH itself, not the South Display, so it shouldn't
apply when there isn't a real PCH.
v3:
- use intel_de_rmw(). [Rodrigo]
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Bob Paauwe <bob.j.paauwe@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201110121700.4338-1-anshuman.gupta@intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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.