redraw issues on i915 since 4.9-rc

[Norbert Preining]

Dear all,

since 4.9-rc series started I see heavy redraw problems on i915. Starting
or resizing for example the digikam window messes up completely the content.

I have seen this at least since rc2 (I often wait till rc2), and 
confirm that 4.8.0 does not exhibit these problems.

A screenshot of the redraw problems is attached.

hardware:
i915 0000:00:02.0: fb0: inteldrmfb frame buffer device

Xorg:
(II) Module modesetting: vendor="X.Org Foundation"
   compiled for 1.18.4, module version = 1.18.4
   Module class: X.Org Video Driver
   ABI class: X.Org Video Driver, version 20.0

00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
	Subsystem: Sony Corporation Haswell-ULT Integrated Graphics Controller
	Flags: bus master, fast devsel, latency 0, IRQ 40
	Memory at df400000 (64-bit, non-prefetchable) [size=4M]
	Memory at e0000000 (64-bit, prefetchable) [size=256M]
	I/O ports at 1000 [size=64]
	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
	Capabilities: [d0] Power Management version 2
	Capabilities: [a4] PCI Advanced Features
	Kernel driver in use: i915

sofware:
Debian/sid uptodate


Thanks a lot

Norbert

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Attachment: digikam-screenshot.jpg
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