Mario Limonciello 9f5595d5f0 platform/x86/amd: pmc: Require at least 2.5 seconds between HW sleep cycles
When an APU exits HW sleep with no active wake sources the Linux kernel will
rapidly assert that the APU can enter back into HW sleep. This happens in a
few ms. Contrasting this to Windows, Windows can take 10s of seconds to
enter back into the resiliency phase for Modern Standby.

For some situations this can be problematic because it can cause leakage
from VDDCR_SOC to VDD_MISC and force VDD_MISC outside of the electrical
design guide specifications. On some designs this will trip the over
voltage protection feature (OVP) of the voltage regulator module, but it
could cause APU damage as well.

To prevent this risk, add an explicit sleep call so that future attempts
to enter into HW sleep will have enough time to settle. This will occur
while the screen is dark and only on cases that the APU should enter HW
sleep again, so it shouldn't be noticeable to any user.

Cc: stable@vger.kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20250414162446.3853194-1-superm1@kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
2025-04-17 14:14:39 +03:00
2024-09-01 20:43:24 -07:00
2025-04-06 10:00:04 -07:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-04-06 13:11:33 -07:00
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.
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