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[ Upstream commit 11c291461b6ea8d1195a96d6bba6673a94aacebc ] There are two modes in which DEVSLP can be entered. The OS initiated or hardware autonomous. In hardware autonomous mode, BIOS configures the AHCI controller and the device to enable DEVSLP. But they may not be ideal for all cases. So in this case, OS should be able to reconfigure DEVSLP register. Currently if the DEVSLP is already enabled, we can't set again as it will simply return. There are some systems where the firmware is setting high DITO by default, in this case we can't modify here to correct settings. With the default in several seconds, we are not able to transition to DEVSLP. This change will allow reconfiguration of devslp register if DITO is different. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Reviewed-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.