[Intel-gfx] Can recent i915 support more than 8192x8192 screen?

[Marcin Owsiany]

sob., 21 lip 2018, 10:20 użytkownik Chris Wilson <chris at chris-wilson.co.uk>
napisał:

> Quoting Rodrigo Vivi (2018-07-20 21:22:25)
> > On Thu, Jul 19, 2018 at 11:31:19PM +0200, Marcin Owsiany wrote:
> > >    Hello,
> > >    TL;DR: how can I set a 8960x2880 screen (not display) size on a
> T580? A
> > >    patch for i915 that I found on the internets does not seem to work.
> > >    Full story:
> > >    I'm a rather happy user of ThinkPad T580 which comes with a
> > >    high-density 3840x2160 LCD, and the following graphics hardware.
> > >    00:02.0 VGA compatible controller: Intel Corporation Device 5917
> (rev
> > >    07) (prog-if 00 [VGA controller])
> > >            Subsystem: Lenovo Device 225a
> > >            Flags: bus master, fast devsel, latency 0, IRQ 142
> > >            Memory at e7000000 (64-bit, non-prefetchable) [size=16M]
> > >            Memory at c0000000 (64-bit, prefetchable) [size=256M]
> > >            I/O ports at e000 [size=64]
> > >            [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
> > >            Capabilities: [40] Vendor Specific Information: Len=0c <?>
> > >            Capabilities: [70] Express Root Complex Integrated Endpoint,
> > >    MSI 00
> > >            Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
> > >            Capabilities: [d0] Power Management version 2
> > >            Capabilities: [100] Process Address Space ID (PASID)
> > >            Capabilities: [200] Address Translation Service (ATS)
> > >            Capabilities: [300] Page Request Interface (PRI)
> > >            Kernel driver in use: i915
> > >            Kernel modules: i915
> > >    Unfortunately attaching it to an external normal-density 2560x1440
> > >    display means I need to apply scaling. Combined with the
> side-by-side
> > >    arrangement of monitors, this means I'd need to set screen size
> > >    to 8960x2880. However this does not work:
> > >     $ xrandr --fb 8960x2880
> > >     xrandr: screen cannot be larger than 8192x8192 (desired size
> > >    8960x2880)
> > >    I found this [1]thread on reddit about the same problem, where a
> user
> > >    posted a simple patch claimed to be supplied by someone on
> #intel-gfx.
> > >    Unfortunately it does not work (or at least is not sufficient) -
> after
> > >    applying it xrandr does claim that 16384x16384 is possible, but
> > >    actually trying to use more than 8192x8192 fails with an error
> > >    (unfortunately I lost the exact message).
> >
> > I'm afraid that it is a hardware limitation that you won't be able to
> > workaround. But a log would be interesting anyway... (both dmesg and
> xorg.0.log)
>
> It is only a hardware limitation for a single pipe. We have supported
> 32kx32k screens for over 6 years in SNA.
>

Do you mean hardware, out Linux X? Does it mean it should be working
already on Linux 4.9.x (x~80)? Or does it depend on Ville's patch set?

Marcin
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