• Hans de Goede's avatar
    platform/x86: Add Intel AtomISP2 dummy / power-management driver · 49ad712a
    Hans de Goede authored
    The Image Signal Processor found on Cherry Trail devices is brought up in
    D0 state on devices which have camera sensors attached to it. The ISP will
    not enter D3 state again without some massaging of its registers beforehand
    and the ISP not being in D3 state blocks the SoC from entering S0ix modes.
    
    There was a driver for the ISP in drivers/staging but that got removed
    again because it never worked. It does not seem likely that a real
    driver for the ISP will be added to the mainline kernel anytime soon.
    
    This commit adds a dummy driver which contains the necessary magic from
    the staging driver to powerdown the ISP, so that Cherry Trail devices where
    the ISP is used will properly use S0ix modes when suspended.
    
    Together with other recent S0ix related fixes this allows S0ix modes to
    be entered on e.g. a Chuwi Hi8 Pro and a HP x2 210.
    
    BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=196915Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Reviewed-by: default avatarAlan Cox <alan@linux.intel.com>
    Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
    49ad712a
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