Re: [PATCH V4] PCI: Add Extended Tags quirk for Broadcom HT2100 Root Port

[Bjorn Helgaas]

On Wed, Jul 12, 2017 at 12:04:14AM -0400, Sinan Kaya wrote:
> All PCIe devices are expected to be able to handle 8-bit tags.
> 'commit 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")'
> enabled extended tags for all devices based on the spec direction.
> 
> The Broadcom HT2100 seems to be having issues with handling
> 8-bit tags. Mark it as broken.
> 
> If a device with extended tags quirk is found, disable extended tags for
> all devices in the tree assuming peer-to-peer is possible.
> 
> The pci_walk_bus() in the quirk handles all devices we've already
> enumerated, and all devices we'll enumerate in the future are handled in
> pci_configure_device().
> 
> Reported-by: Wim ten Have <wim.ten.have@xxxxxxxxxx>
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1467674
> Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>

Applied with Wim's tested-by to pci/enumeration for v4.14, thanks!

> ---
>  drivers/pci/pci.h    |  1 +
>  drivers/pci/probe.c  | 35 ++++++++++++++++++++++++++++++-----
>  drivers/pci/quirks.c | 19 +++++++++++++++++++
>  include/linux/pci.h  |  1 +
>  4 files changed, 51 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index f8113e5..7153c92 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -239,6 +239,7 @@ 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 19c8950..bc067fb 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1684,22 +1684,47 @@ 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)
>  {
> +	struct pci_host_bridge *host;
>  	u32 dev_cap;
>  	int ret;
> +	u16 ctl;
>  
>  	if (!pci_is_pcie(dev))
> -		return;
> +		return 0;
>  
>  	ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &dev_cap);
>  	if (ret)
> -		return;
> +		return 0;
> +
> +	if (!(dev_cap & PCI_EXP_DEVCAP_EXT_TAG))
> +		return 0;
> +
> +	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 (dev_cap & PCI_EXP_DEVCAP_EXT_TAG)
> +	if (host->broken_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;
>  }
> +EXPORT_SYMBOL(pci_configure_extended_tags);
>  
>  static void pci_configure_device(struct pci_dev *dev)
>  {
> @@ -1707,7 +1732,7 @@ 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 085fb78..b5dc99c 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4664,3 +4664,22 @@ 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_exttags_completer(struct pci_dev *pdev)
> +{
> +	struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
> +
> +	if (!bridge)
> +		return;
> +
> +	bridge->broken_ext_tags = 1;
> +	dev_info(&pdev->dev, "Extended Tag handling is broken\n");
> +
> +	pci_walk_bus(bridge->bus, pci_configure_extended_tags, NULL);
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0140,
> +			quirk_exttags_completer);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0142,
> +			quirk_exttags_completer);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0144,
> +			quirk_exttags_completer);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 8039f9f..2b22c3e 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -441,6 +441,7 @@ struct pci_host_bridge {
>  	void *release_data;
>  	struct msi_controller *msi;
>  	unsigned int ignore_reset_delay:1;	/* for entire hierarchy */
> +	unsigned int broken_ext_tags:1;
>  	/* Resource alignment requirements */
>  	resource_size_t (*align_resource)(struct pci_dev *dev,
>  			const struct resource *res,
> -- 
> 1.9.1
> 
> 
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