On Fri, Oct 09, 2020 at 12:01:39PM +0200, Daniel Vetter wrote: > On Fri, Oct 9, 2020 at 11:47 AM Ville Syrjälä > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > On Fri, Oct 09, 2020 at 09:59:34AM +0200, Daniel Vetter wrote: > > > When trying to test my CONFIG_IO_STRICT_DEVMEM changes I realized they > > > do nothing for i915. Because i915 doesn't request any regions, like > > > pretty much all drm pci drivers. I guess this is some very old > > > remnants from the userspace modesetting days, when we wanted to > > > co-exist with the fbdev driver. Which usually requested these > > > resources. > > > > > > But makes me wonder why the pci subsystem doesn't just request > > > resource automatically when we map a bar and a pci driver is bound? > > > > > > Knowledge about which pci bars we need kludged together from > > > intel_uncore.c and intel_gtt.c from i915 and intel-gtt.c over in the > > > fake agp driver. > > > > > > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > > > Cc: Jason Gunthorpe <jgg@xxxxxxxx> > > > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > > Cc: John Hubbard <jhubbard@xxxxxxxxxx> > > > Cc: Jérôme Glisse <jglisse@xxxxxxxxxx> > > > Cc: Jan Kara <jack@xxxxxxx> > > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > > > Cc: linux-mm@xxxxxxxxx > > > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > > Cc: linux-samsung-soc@xxxxxxxxxxxxxxx > > > Cc: linux-media@xxxxxxxxxxxxxxx > > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > Cc: linux-pci@xxxxxxxxxxxxxxx > > > --- > > > drivers/gpu/drm/i915/intel_uncore.c | 25 +++++++++++++++++++++++-- > > > 1 file changed, 23 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c > > > index 54e201fdeba4..ce39049d8919 100644 > > > --- a/drivers/gpu/drm/i915/intel_uncore.c > > > +++ b/drivers/gpu/drm/i915/intel_uncore.c > > > @@ -1692,10 +1692,13 @@ static int uncore_mmio_setup(struct intel_uncore *uncore) > > > struct pci_dev *pdev = i915->drm.pdev; > > > int mmio_bar; > > > int mmio_size; > > > + int bar_selection; > > > > Signed bitmasks always make me uneasy. But looks like > > that's what it is in the pci api. So meh. > > Yeah it's surprising. > > > > + int ret; > > > > > > mmio_bar = IS_GEN(i915, 2) ? 1 : 0; > > > + bar_selection = BIT (2) | BIT(mmio_bar); > > ^ > > spurious space > > > > That's also not correct for gen2 I think. > > > > gen2: > > 0 = GMADR > > 1 = MMADR > > 2 = IOBAR > > > > gen3: > > 0 = MMADR > > 1 = IOBAR > > 2 = GMADR > > 3 = GTTADR > > > > gen4+: > > 0+1 = GTTMMADR > > 2+3 = GMADR > > 4 = IOBAR > > > > Maybe we should just have an explicit list of bars like that in a > > comment? > > > > I'd also suggest sucking this bitmask calculation into a small helper > > so you can reuse it for the release. > > tbh I just hacked this up for testing. Given how almost no other drm > driver does this, I'm wondering whether we should or not. > > Also the only reason why I didn't just use the pci_request_regions > helper is to avoid the vga ioport range, since that's managed by > vgaarbiter. VGA io range isn't part of any bar. Or do you mean just the io decode enable bit in the pci command register? That should be just a matter or pci_enable_device() vs. pci_enable_device_mem() I think. So nothing to do with which bars we've requested IIRC. > > So I think if we go for this for real we should: > - register the vga ioport range in the vgaarbiter > - have a pci_request_iomem_regions helper that grabs all mem bars > - roll that out to all drm pci drivers > > Or something like that. The other complication is when we resize the > iobar. So not really sure what to do here. We resize it? -- Ville Syrjälä Intel
