20e1aec964
[ Upstream commit c763729a10e538d997744317cf4a1c4f25266066 ] Currently, ufshcd-pci is the only UFS driver with support for suspend-to-disk PM callbacks (i.e. freeze/thaw/restore/poweroff). These callbacks are set by the macro SET_SYSTEM_SLEEP_PM_OPS to the same functions as system suspend/resume. That will work with spm_lvl 5 because spm_lvl 5 will result in a full restore for the ->restore() callback. In the absence of a full restore, the host controller registers will have values set up by the restore kernel (the kernel that boots and loads the restore image) which are not necessarily the same. However it turns out, the only registers that sometimes need restore are the base address registers. This has gone un-noticed because, depending on IOMMU settings, the kernel can end up allocating the same addresses every time. For Intel controllers, an spm_lvl other than 5 can be used, so to support S4 (suspend-to-disk) with spm_lvl other than 5, restore the base address registers. Link: https://lore.kernel.org/r/20201207083120.26732-2-adrian.hunter@intel.com Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.