Re: [PATCH] drm/vmwgfx: Stop requesting the pci regions

[Zack Rusin <zackr@vmware.com>]

On Wed, 2022-01-19 at 17:36 +0100, Javier Martinez Canillas wrote:
> On 1/19/22 16:50, Thomas Zimmermann wrote:
> 
> [snip]
> 
> > > > > IMHO the best solution is to drop IORESOURCE_BUSY from sysfb
> > > > > and have
> > > > > drivers register/release the range with _BUSY. That would
> > > > > signal the
> > > > > memory belongs to the sysfb device but is not busy unless a
> > > > > driver
> > > > > has
> > > > > been bound. After simplefb released the range, it should be
> > > > > 'non-
> > > > > busy'
> > > > > again and available for vmwgfx. Simpledrm does a hot-unplug of
> > > > > the
> > > > > sysfb
> > > > > device, so the memory range gets released entirely. If you
> > > > > want, I'll
> > > > > prepare some patches for this scenario.
> > > > 
> > > > Attached is a patch that implements this. Doing
> > > > 
> > > >    cat /proc/iomem
> > > >     ...
> > > >     e0000000-efffffff : 0000:00:02.0
> > > > 
> > > >       e0000000-e07e8fff : BOOTFB
> > > > 
> > > >         e0000000-e07e8fff : simplefb
> > > > 
> > > >     ...
> > > > 
> > > > shows the memory. 'BOOTFB' is the simple-framebuffer device and
> > > > 'simplefb' is the driver. Only the latter uses _BUSY. Same for
> > > > and the memory canbe acquired by vmwgfx.
> > > > 
> > > > Zack, please test this patch. If it works, I'll send out the real
> > > > patchset.
> > > 
> > > Hmm, the patch looks good but it doesn't work. After boot:
> > > /proc/iomem
> > > 50000000-7fffffff : pcie@0x40000000
> > >    78000000-7fffffff : 0000:00:0f.0
> > >      78000000-782fffff : BOOTFB
> > > 
> > > and vmwgfx fails on pci_request_regions:
> > > 
> > > kernel: fb0: switching to vmwgfx from simple
> > > kernel: Console: switching to colour dummy device 80x25
> > > kernel: vmwgfx 0000:00:0f.0: BAR 2: can't reserve [mem 0x78000000-
> > > 0x7fffffff 64bit pref]
> > > kernel: vmwgfx: probe of 0000:00:0f.0 failed with error -16
> > > 
> > > leaving the system without a fb driver.
> > 
> > OK, I suspect that it would work if you use simpledrm instead of 
> > simplefb. Could you try please? You'd have to build DRM and simpledrm
> > into the kernel binary.
> > 
> 
> Yes, I believe that should work.
>  Zack, could you please try if just the following [0] make it works ?

Unfortunately that still fails with the same:
kernel: fb0: switching to vmwgfx from simple
kernel: Console: switching to colour dummy device 80x25
kernel: vmwgfx 0000:00:0f.0: BAR 2: can't reserve [mem 0x78000000-
0x7fffffff 64bit pref]
kernel: vmwgfx: probe of 0000:00:0f.0 failed with error -16

z