On Sun, 14 Oct 2018 19:54:27 +0200 Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > 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=196915 > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> Reviewed-by: Alan Cox <alan@xxxxxxxxxxxxxxx> Thanks
