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Message-ID: <CABawtvPf2UXZif1GpdNQ5g+yZWyf7fLWNgxaYp3NTsWczu0S9A@mail.gmail.com>
Date: Thu, 13 Jul 2017 13:54:17 +0800
From: Ethan Zhao <ethan.kernel@...il.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Sinan Kaya <okaya@...eaurora.org>,
Wim ten Have <wim.ten.have@...cle.com>,
linux-pci <linux-pci@...r.kernel.org>, timur@...eaurora.org,
LKML <linux-kernel@...r.kernel.org>,
linux-arm-msm@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V4] PCI: Add Extended Tags quirk for Broadcom HT2100 Root Port
On Thu, Jul 13, 2017 at 3:34 AM, Bjorn Helgaas <helgaas@...nel.org> wrote:
> On Wed, Jul 12, 2017 at 08:15:43AM -0400, Sinan Kaya wrote:
>> On 7/12/2017 5:44 AM, Ethan Zhao wrote:
>> > The dmesg yelled "...Tag handling is broken" , but didn't say how it
>> > was handled, that is weird and confusing, just because there is no
>> > device under that bridge ?
>> >
>> > How about move the messages together "...is broken, disable Extended tag..."
>
> I changed the message this:
>
> pci 0000:00:07.0: disabling Extended Tags (this device can't handle them)
>
> We don't see any message from 0000:01:00.0 itself because it powered up
> with Extended Tags disabled. If it powered up with Extended Tags *enabled*
> (as allowed by the ECN), we would see this:
>
> pci 0000:00:07.0: disabling Extended Tags (this device can't handle them)
> pci 0000:01:00.0: disabling Extended Tags
>
> Does that seem reasonable? Complete updated patch attached below.
>
>> This was something requested by Bjorn to inform that user has a broken HW
>> when a quirk is matched.
>>
>> The new code will disable extended tags only if it was enabled on endpoint
>> via power on reset value or via some broken BIOS.
>>
>> It looks like we are not seeing any disabling message. This implies that
>> both the card and BIOS is good.
>>
>> That's why, you are no longer seeing a disabling message on this system
>> and code is just not enabling extended tags.
>
>
> commit 2e6e588b99c4c7fbcea55eb48890fa8d0ab0c3d7
> Author: Sinan Kaya <okaya@...eaurora.org>
> Date: Wed Jul 12 00:04:14 2017 -0400
>
> PCI: Mark Broadcom HT2100 Root Port Extended Tags as broken
>
> Per PCIe r3.1, sec 2.2.6.2 and 7.8.4, a Requester may not use 8-bit Tags
> unless its Extended Tag Field Enable is set, but all Receivers/Completers
> must handle 8-bit Tags correctly regardless of their Extended Tag Field
> Enable.
>
> Some devices do not handle 8-bit Tags as Completers, so add a quirk for
> them. If we find such a device, we disable Extended Tags for the entire
> hierarchy to make peer-to-peer DMA possible.
>
> The Broadcom HT2100 seems to have issues with handling 8-bit tags. Mark it
> as broken.
>
> The pci_walk_bus() in the quirk handles devices we've enumerated in the
> past, and pci_configure_device() handles devices we enumerate in the
> future.
>
> Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1467674
> Reported-and-tested-by: Wim ten Have <wim.ten.have@...cle.com>
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> [bhelgaas: changelog, tweak messages, rename bit and quirk]
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 03e3d0285aea..9c3d123d358f 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -234,6 +234,7 @@ enum pci_bar_type {
> pci_bar_mem64, /* A 64-bit memory BAR */
> };
>
> +int pci_configure_extended_tags(struct pci_dev *dev, void *ign);
> bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *pl,
> int crs_timeout);
> int pci_setup_device(struct pci_dev *dev);
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index c31310db0404..c81c9835f4c7 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1745,21 +1745,50 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
> */
> }
>
> -static void pci_configure_extended_tags(struct pci_dev *dev)
> +int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
> {
> - u32 dev_cap;
> + struct pci_host_bridge *host;
> + u32 cap;
> + u16 ctl;
> int ret;
>
> if (!pci_is_pcie(dev))
> - return;
> + return 0;
>
> - ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &dev_cap);
> + ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
> if (ret)
> - return;
> + return 0;
> +
> + if (!(cap & PCI_EXP_DEVCAP_EXT_TAG))
> + return 0;
>
> - if (dev_cap & PCI_EXP_DEVCAP_EXT_TAG)
> + ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
> + if (ret)
> + return 0;
> +
> + host = pci_find_host_bridge(dev->bus);
> + if (!host)
> + return 0;
> +
> + /*
> + * If some device in the hierarchy doesn't handle Extended Tags
> + * correctly, make sure they're disabled.
> + */
> + if (host->no_ext_tags) {
> + if (ctl & PCI_EXP_DEVCTL_EXT_TAG) {
> + dev_info(&dev->dev, "disabling Extended Tags\n");
> + pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
> + PCI_EXP_DEVCTL_EXT_TAG);
> + }
> + return 0;
> + }
> +
> + if (!(ctl & PCI_EXP_DEVCTL_EXT_TAG)) {
> + dev_info(&dev->dev, "enabling Extended Tags\n");
> pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
> PCI_EXP_DEVCTL_EXT_TAG);
> + }
> + return 0;
> }
>
> static void pci_configure_device(struct pci_dev *dev)
> @@ -1768,7 +1797,7 @@ static void pci_configure_device(struct pci_dev *dev)
> int ret;
>
> pci_configure_mps(dev);
> - pci_configure_extended_tags(dev);
> + pci_configure_extended_tags(dev, NULL);
>
> memset(&hpp, 0, sizeof(hpp));
> ret = pci_get_hp_params(dev, &hpp);
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 6967c6b4cf6b..f135765555c9 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4681,3 +4681,19 @@ static void quirk_intel_no_flr(struct pci_dev *dev)
> }
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr);
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr);
> +
> +static void quirk_no_ext_tags(struct pci_dev *pdev)
> +{
> + struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
> +
> + if (!bridge)
> + return;
> +
> + bridge->no_ext_tags = 1;
> + dev_info(&pdev->dev, "disabling Extended Tags (this device can't handle them)\n");
A late 'Great !', at least we get reason - (this device can't handle
them) and result - (disabling Extended Tags) at the same time, feel
better.
Thanks,
Ethan
> +
> + pci_walk_bus(bridge->bus, pci_configure_extended_tags, NULL);
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0140, quirk_no_ext_tags);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0142, quirk_no_ext_tags);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0144, quirk_no_ext_tags);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 4869e66dd659..3b968d435895 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -451,6 +451,7 @@ struct pci_host_bridge {
> void *release_data;
> struct msi_controller *msi;
> unsigned int ignore_reset_delay:1; /* for entire hierarchy */
> + unsigned int no_ext_tags:1; /* no Extended Tags */
> /* Resource alignment requirements */
> resource_size_t (*align_resource)(struct pci_dev *dev,
> const struct resource *res,
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