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Date: Wed, 4 Feb 2015 10:50:16 -0700
From: Myron Stowe <myron.stowe@...il.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Myron Stowe <myron.stowe@...hat.com>,
linux-pci <linux-pci@...r.kernel.org>,
Nick Alcock <nix@...eri.org.uk>,
LKML <linux-kernel@...r.kernel.org>,
Andres Salomon <dilinger@...ued.net>,
Leigh Porter <leigh@...ghporter.org>,
Jens Rottmann <JRottmann@...pertembedded.de>,
Bill Unruh <unruh@...sics.ubc.ca>,
Martin Lucina <martin@...ina.net>,
Matthew Wilcox <willy@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] PCI: Expand quirk's handling of CS553x devices
On Tue, Feb 3, 2015 at 9:04 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> [+cc Andres, Leigh, Jens because they were involved in 73d2eaac8a3f
> ("CS5536: apply pci quirk for BIOS SMBUS bug")]
>
> [+cc Bill, Martin, Matthew, Greg, Linus because they saw the original
> report and might be interested in the resolution]
>
> On Tue, Feb 03, 2015 at 04:01:24PM -0700, Myron Stowe wrote:
>> There seem to be a number of issues with CS553x devices and due to a
>> recent patch series that detects PCI read-only BARs [1], we've encountered
>> more.
>>
>> It appears that not only are the BAR values associated with this device
>> often greater than the largest range that an IO decoder can request, they
>> can also be non-conformant with respect to PCI's BAR sizing aspects,
>> behaving instead, in a read-only manner [2].
>>
>> This patch addresses read-only BAR values corresponding to CS553x devices
>> by expanding the existing quirk, manually inserting regions based on the
>> device's BIOS settings (as opposed to basing such on normal BAR sizing
>> actions) when necessary.
>>
>> [1] https://lkml.org/lkml/2014/10/30/637
>> [PATCH 0/3] PCI: Fix detection of read-only BARs
>> 36e8164882ca PCI: Restore detection of read-only BARs
>> f795d86aaa57 PCI: Shrink decoding-disabled window while sizing BARs
>> 7e79c5f8cad2 PCI: Add informational printk for invalid BARs
>> [2] https://bugzilla.kernel.org/show_bug.cgi?id=85991 (Comment #4 forward)
>> Reference: support.amd.com/TechDocs/31506_cs5535_databook.pdf
>>
>> Reported-by: Nix <nix@...eri.org.uk>
>> Signed-off-by: Myron Stowe <myron.stowe@...hat.com>
>> Fixes: 36e8164882ca ("PCI: Restore detection of read-only BARs")
>> CC: stable@...r.kernel.org # v.2.6.27+
>> ---
>> drivers/pci/quirks.c | 40 +++++++++++++++++++++++++++++++++++++---
>> 1 file changed, 37 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index ed6f89b..aac98c5 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -324,18 +324,52 @@ static void quirk_s3_64M(struct pci_dev *dev)
>> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_S3, PCI_DEVICE_ID_S3_868, quirk_s3_64M);
>> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_S3, PCI_DEVICE_ID_S3_968, quirk_s3_64M);
>>
>> +static void quirk_io(struct pci_dev *dev, int pos, unsigned size,
>> + const char *name)
>> +{
>> + u32 region;
>> + struct pci_bus_region bus_region;
>> + struct resource *res = dev->resource + pos;
>> +
>> + pci_read_config_dword(dev, PCI_BASE_ADDRESS_0 + (pos << 2), ®ion);
>> +
>> + if (!region)
>> + return;
>> +
>> + res->name = pci_name(dev);
>> + res->flags = region & ~PCI_BASE_ADDRESS_IO_MASK;
>> + res->flags |=
>> + (IORESOURCE_IO | IORESOURCE_PCI_FIXED | IORESOURCE_SIZEALIGN);
>> + region &= ~(size - 1);
>> +
>> + /* Convert from PCI bus to resource space */
>> + bus_region.start = region;
>> + bus_region.end = region + size - 1;
>> + pcibios_bus_to_resource(dev->bus, res, &bus_region);
>> +
>> + dev_info(&dev->dev, FW_BUG "%s quirk: reg 0x%x: %pR\n",
>> + name, PCI_BASE_ADDRESS_0 + (pos << 2), res);
>> +}
>> +
>> /*
>> * Some CS5536 BIOSes (for example, the Soekris NET5501 board w/ comBIOS
>> * ver. 1.33 20070103) don't set the correct ISA PCI region header info.
>> * BAR0 should be 8 bytes; instead, it may be set to something like 8k
>> * (which conflicts w/ BAR1's memory range).
>> + *
>> + * CS553x's ISA PCI BARs may also be read-only (ref:
>> + * https://bugzilla.kernel.org/show_bug.cgi?id=85991 - Comment #4 forward).
>> */
>> static void quirk_cs5536_vsa(struct pci_dev *dev)
>> {
>> + static char *name = "CS5536 ISA bridge";
>> +
>> if (pci_resource_len(dev, 0) != 8) {
>> - struct resource *res = &dev->resource[0];
>> - res->end = res->start + 8 - 1;
>> - dev_info(&dev->dev, "CS5536 ISA bridge bug detected (incorrect header); workaround applied\n");
>> + quirk_io(dev, 0, 8, name);
>> + quirk_io(dev, 1, 256, name);
>> + quirk_io(dev, 2, 512, name);
>
> Per sec 5.6.1 of the datasheets, I think BAR 2 (MFGPT) is only 64 bytes.
>
> On Nix's system, we detected it as 512 bytes prior to 36e8164882ca. That
> was because the BAR contained 0x6200, and the lowest-order set bit
> determines the BAR size, so it was 512 in that case. So forcing it to be
> 512 certainly works on Nix's system (though it may consume unnecessary
> space after the BAR).
>
> But this quirk ONLY works if the system makes that BAR 512-byte aligned.
> If the BAR is at an address that is only aligned to 64 bytes, not 512, this
> quirk will forcibly align the start to 512. For example, if we had:
>
> pci 0000:00:14.0: reg 0x18: [io 0x6240-0x627f] (a read-only BAR)
>
> this quirk would read 0x6240 from the BAR and align it to 0x6200 (the
> "region &= ~(size - 1)" part) so we end up with [io 0x6200-0x63ff]. I
> don't think that will work.
Agreed, we had talked about the current sizes being out-of-range (too large) for
two of the BARs. I was trying to be safe and not screw up more than I
had already
by sticking with the existing, known working, values. I hadn't
thought through the
ramifications going forward with respect to alignment however. Nice catch!
>
> I tweaked the patch (as below) and applied to my for-linus branch for
> v3.19. I haven't asked Linus to pull it yet, so let me know if we still
> need to tweak it some more.
>
> Bjorn
>
>> + dev_info(&dev->dev, "%s bug detected (incorrect header); workaround applied\n",
>> + name);
>> }
>> }
>> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA, quirk_cs5536_vsa);
>>
>
>
> commit f13ad4b2718e5900c1b8a8eeb500860145a5991f
> Author: Myron Stowe <myron.stowe@...hat.com>
> Date: Tue Feb 3 16:01:24 2015 -0700
>
> PCI: Handle read-only BARs on AMD CS553x devices
>
> Some AMD CS553x devices have read-only BARs because of a firmware or
> hardware defect. There's a workaround in quirk_cs5536_vsa(), but it no
> longer works after 36e8164882ca ("PCI: Restore detection of read-only
> BARs"). Prior to 36e8164882ca, we filled in res->start; afterwards we
> leave it zeroed out. The quirk only updated the size, so the driver tried
> to use a region starting at zero, which didn't work.
>
> Expand quirk_cs5536_vsa() to read the base addresses from the BARs and
> hard-code the sizes.
>
> Prior to 36e8164882ca, BAR 2 was detected as 512 bytes based on a read-only
> BAR value of 0x6200. The lowest-order set bit determines the largest
> possible BAR size: 512 in this case. Per sec 5.6.1 of the datasheets, I
> think BAR 2 (MFGPT) requires only 64 bytes, so set the resource to that.
> If a platform puts this BAR at only 64-byte alignment, we don't want to
> align the address to 512 bytes by throwing away those low-order bits.
>
> [bhelgaas: changelog, reduce BAR 2 size to 64]
> Fixes: 36e8164882ca ("PCI: Restore detection of read-only BARs")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=85991#c4
> Link: http://support.amd.com/TechDocs/31506_cs5535_databook.pdf
> Link: http://support.amd.com/TechDocs/33238G_cs5536_db.pdf
> Reported-and-tested-by: Nix <nix@...eri.org.uk>
> Signed-off-by: Myron Stowe <myron.stowe@...hat.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> CC: stable@...r.kernel.org # v.2.6.27+
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index e52356aa09b8..903d5078b5ed 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -324,18 +324,52 @@ static void quirk_s3_64M(struct pci_dev *dev)
> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_S3, PCI_DEVICE_ID_S3_868, quirk_s3_64M);
> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_S3, PCI_DEVICE_ID_S3_968, quirk_s3_64M);
>
> +static void quirk_io(struct pci_dev *dev, int pos, unsigned size,
> + const char *name)
> +{
> + u32 region;
> + struct pci_bus_region bus_region;
> + struct resource *res = dev->resource + pos;
> +
> + pci_read_config_dword(dev, PCI_BASE_ADDRESS_0 + (pos << 2), ®ion);
> +
> + if (!region)
> + return;
> +
> + res->name = pci_name(dev);
> + res->flags = region & ~PCI_BASE_ADDRESS_IO_MASK;
> + res->flags |=
> + (IORESOURCE_IO | IORESOURCE_PCI_FIXED | IORESOURCE_SIZEALIGN);
> + region &= ~(size - 1);
> +
> + /* Convert from PCI bus to resource space */
> + bus_region.start = region;
> + bus_region.end = region + size - 1;
> + pcibios_bus_to_resource(dev->bus, res, &bus_region);
> +
> + dev_info(&dev->dev, FW_BUG "%s quirk: reg 0x%x: %pR\n",
> + name, PCI_BASE_ADDRESS_0 + (pos << 2), res);
> +}
> +
> /*
> * Some CS5536 BIOSes (for example, the Soekris NET5501 board w/ comBIOS
> * ver. 1.33 20070103) don't set the correct ISA PCI region header info.
> * BAR0 should be 8 bytes; instead, it may be set to something like 8k
> * (which conflicts w/ BAR1's memory range).
> + *
> + * CS553x's ISA PCI BARs may also be read-only (ref:
> + * https://bugzilla.kernel.org/show_bug.cgi?id=85991 - Comment #4 forward).
> */
> static void quirk_cs5536_vsa(struct pci_dev *dev)
> {
> + static char *name = "CS5536 ISA bridge";
> +
> if (pci_resource_len(dev, 0) != 8) {
> - struct resource *res = &dev->resource[0];
> - res->end = res->start + 8 - 1;
> - dev_info(&dev->dev, "CS5536 ISA bridge bug detected (incorrect header); workaround applied\n");
> + quirk_io(dev, 0, 8, name); /* SMB */
> + quirk_io(dev, 1, 256, name); /* GPIO */
> + quirk_io(dev, 2, 64, name); /* MFGPT */
> + dev_info(&dev->dev, "%s bug detected (incorrect header); workaround applied\n",
> + name);
> }
> }
> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA, quirk_cs5536_vsa);
> --
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