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Listen for PMIC bus access notifications and get FORCEWAKE_ALL while the bus is accessed to avoid needing to do any forcewakes, which need PMIC bus access, while the PMIC bus is busy: This fixes errors like these showing up in dmesg, usually followed by a gfx or system freeze: [drm:fw_domains_get [i915]] *ERROR* render: timed out waiting for forcewake ack request. [drm:fw_domains_get [i915]] *MEDIA* render: timed out waiting for forcewake ack request. i2c_designware 808622C1:06: punit semaphore timed out, resetting i2c_designware 808622C1:06: PUNIT SEM: 2 i2c_designware 808622C1:06: couldn't acquire bus ownership Downside of this approach is that it causes wakeups whenever the PMIC bus is accessed. Unfortunately we cannot simply wait for the PMIC bus to go idle when we hit a race, as forcewakes may be done from interrupt handlers where we cannot sleep to wait for the i2c PMIC bus access to finish. Note that the notifications and thus the wakeups will only happen on baytrail / cherrytrail devices using PMICs with a shared i2c bus for P-Unit and host PMIC access (i2c busses with a _SEM method in their APCI node), e.g. an axp288 PMIC. I plan to write some patches for drivers accessing the PMIC bus to limit their bus accesses to a bare minimum (e.g. cache registers, do not update battery level more often then 4 times a minute), to limit the amount of wakeups. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=155241 Signed-off-by: Hans de Goede <hdegoede@redhat.com> Tested-by: tagorereddy <tagore.chandan@gmail.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> [danvet: Wiggle in conflicts.] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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.