Messages in this thread | | | Date | Sun, 17 Jan 2021 20:27:18 +0100 | From | Michael Walle <> | Subject | Re: [PATCH v2] PCI: Fix Intel i210 by avoiding overlapping of BARs |
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Hi Bjorn,
Am 2021-01-16 00:57, schrieb Bjorn Helgaas: > On Wed, Jan 13, 2021 at 12:32:32AM +0100, Michael Walle wrote: >> Am 2021-01-12 23:58, schrieb Bjorn Helgaas: >> > On Sat, Jan 09, 2021 at 07:31:46PM +0100, Michael Walle wrote: >> > > Am 2021-01-08 22:20, schrieb Bjorn Helgaas: > >> > > > 3) If the Intel i210 is defective in how it handles an Expansion ROM >> > > > that overlaps another BAR, a quirk might be the right fix. But my >> > > > guess is the device is working correctly per spec and there's >> > > > something wrong in how firmware/Linux is assigning things. That would >> > > > mean we need a more generic fix that's not a quirk and not tied to the >> > > > Intel i210. >> > > >> > > Agreed, but as you already stated (and I've also found that in >> > > the PCI spec) the Expansion ROM address decoder can be shared by >> > > the other BARs and it shouldn't matter as long as the ExpROM BAR >> > > is disabled, which is the case here. >> > >> > My point is just that if this could theoretically affect devices >> > other than the i210, the fix should not be an i210-specific quirk. >> > I'll assume this is a general problem and wait for a generic PCI >> > core solution unless it's i210-specific. >> >> I guess the culprit here is that linux skips the programming of the >> BAR because of some broken Matrox card. That should have been a >> quirk instead, right? But I don't know if we want to change that, do >> we? How many other cards depend on that? > > Oh, right. There's definitely some complicated history there that > makes me a little scared to change things. But it's also unfortunate > if we have to pile quirks on top of quirks. > >> And still, how do we find out that the i210 is behaving correctly? >> In my opinion it is clearly not. You can change the ExpROM BAR value >> during runtime and it will start working (while keeping it >> disabled). Am I missing something here? > > I agree; if the ROM BAR is disabled, I don't think it should matter at > all what it contains, so this does look like an i210 defect. > > Would you mind trying the patch below? It should update the ROM BAR > value even when it is disabled. With the current pci_enable_rom() > code that doesn't rely on the value read from the BAR, I *think* this > should be safe even on the Matrox and similar devices.
Your patch will fix my issue:
Tested-by: Michael Walle <michael@walle.cc>
> > commit 0ca2233eb71f ("PCI: Update ROM BAR even if disabled") > Author: Bjorn Helgaas <bhelgaas@google.com> > Date: Fri Jan 15 17:17:44 2021 -0600 > > PCI: Update ROM BAR even if disabled > > Test patch for i210 issue reported by Michael Walle: > https://lore.kernel.org/r/20201230185317.30915-1-michael@walle.cc > > diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c > index 8fc9a4e911e3..fc638034628c 100644 > --- a/drivers/pci/rom.c > +++ b/drivers/pci/rom.c > @@ -35,9 +35,8 @@ int pci_enable_rom(struct pci_dev *pdev) > return 0; > > /* > - * Ideally pci_update_resource() would update the ROM BAR address, > - * and we would only set the enable bit here. But apparently some > - * devices have buggy ROM BARs that read as zero when disabled. > + * Some ROM BARs read as zero when disabled, so we can't simply > + * read the BAR, set the enable bit, and write it back. > */ > pcibios_resource_to_bus(pdev->bus, ®ion, res); > pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr); > diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c > index 7f1acb3918d0..f69b7d179617 100644 > --- a/drivers/pci/setup-res.c > +++ b/drivers/pci/setup-res.c > @@ -69,18 +69,10 @@ static void pci_std_update_resource(struct pci_dev > *dev, int resno) > if (resno < PCI_ROM_RESOURCE) { > reg = PCI_BASE_ADDRESS_0 + 4 * resno; > } else if (resno == PCI_ROM_RESOURCE) { > - > - /* > - * Apparently some Matrox devices have ROM BARs that read > - * as zero when disabled, so don't update ROM BARs unless > - * they're enabled. See > - * https://lore.kernel.org/r/43147B3D.1030309@vc.cvut.cz/ > - */ > - if (!(res->flags & IORESOURCE_ROM_ENABLE)) > - return; > + if (res->flags & IORESOURCE_ROM_ENABLE) > + new |= PCI_ROM_ADDRESS_ENABLE; > > reg = dev->rom_base_reg; > - new |= PCI_ROM_ADDRESS_ENABLE; > } else > return; > > @@ -99,7 +91,8 @@ static void pci_std_update_resource(struct pci_dev > *dev, int resno) > pci_write_config_dword(dev, reg, new); > pci_read_config_dword(dev, reg, &check); > > - if ((new ^ check) & mask) { > + /* Some ROM BARs read as zero when disabled */ > + if (resno != PCI_ROM_RESOURCE && (new ^ check) & mask) { > pci_err(dev, "BAR %d: error updating (%#08x != %#08x)\n", > resno, new, check); > }
-- -michael
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