On Fri, Oct 9, 2020 at 11:47 AM Ville Syrjälä ville.syrjala@linux.intel.com 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@intel.com Cc: Jason Gunthorpe jgg@ziepe.ca Cc: Kees Cook keescook@chromium.org Cc: Dan Williams dan.j.williams@intel.com Cc: Andrew Morton akpm@linux-foundation.org Cc: John Hubbard jhubbard@nvidia.com Cc: Jérôme Glisse jglisse@redhat.com Cc: Jan Kara jack@suse.cz Cc: Dan Williams dan.j.williams@intel.com Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Bjorn Helgaas bhelgaas@google.com Cc: linux-pci@vger.kernel.org
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.
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. -Daniel
/*
* Before gen4, the registers and the GTT are behind different BARs.
* On gen3 the registers and the GTT are behind different BARs. * However, from gen4 onwards, the registers and the GTT are shared * in the same BAR, so we want to restrict this ioremap from * clobbering the GTT which we want ioremap_wc instead. Fortunately,@@ -1703,6 +1706,8 @@ static int uncore_mmio_setup(struct intel_uncore *uncore) * generations up to Ironlake. * For dgfx chips register range is expanded to 4MB. */
if (INTEL_GEN(i915) == 3)bar_selection |= BIT(3); if (INTEL_GEN(i915) < 5) mmio_size = 512 * 1024; else if (IS_DGFX(i915))@@ -1710,8 +1715,15 @@ static int uncore_mmio_setup(struct intel_uncore *uncore) else mmio_size = 2 * 1024 * 1024;
ret = pci_request_selected_regions(pdev, bar_selection, "i915");if (ret < 0) {drm_err(&i915->drm, "failed to request pci bars\n");return ret;}uncore->regs = pci_iomap(pdev, mmio_bar, mmio_size); if (uncore->regs == NULL) {pci_release_selected_regions(pdev, bar_selection); drm_err(&i915->drm, "failed to map registers\n"); return -EIO; }@@ -1721,9 +1733,18 @@ static int uncore_mmio_setup(struct intel_uncore *uncore)
static void uncore_mmio_cleanup(struct intel_uncore *uncore) {
struct pci_dev *pdev = uncore->i915->drm.pdev;
struct drm_i915_private *i915 = uncore->i915;struct pci_dev *pdev = i915->drm.pdev;int mmio_bar;int bar_selection;mmio_bar = IS_GEN(i915, 2) ? 1 : 0;bar_selection = BIT (2) | BIT(mmio_bar);if (INTEL_GEN(i915) == 3)bar_selection |= BIT(3); pci_iounmap(pdev, uncore->regs);pci_release_selected_regions(pdev, bar_selection);}
void intel_uncore_init_early(struct intel_uncore *uncore,
2.28.0
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- Ville Syrjälä Intel