netdev - Re: linux-next: manual merge of the pci tree with the net tree

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Date:   Mon, 4 Sep 2017 14:54:27 +1000
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        David Miller <davem@...emloft.net>,
        Networking <netdev@...r.kernel.org>
Cc:     Linux-Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ding Tianhong <dingtianhong@...wei.com>,
        Casey Leedom <leedom@...lsio.com>,
        Sinan Kaya <okaya@...eaurora.org>
Subject: Re: linux-next: manual merge of the pci tree with the net tree

Hi all,

On Wed, 16 Aug 2017 09:51:28 +1000 Stephen Rothwell <sfr@...b.auug.org.au> wrote:
>
> Today's linux-next merge of the pci tree got a conflict in:
> 
>   drivers/pci/probe.c
> 
> between commit:
> 
>   a99b646afa8a ("PCI: Disable PCIe Relaxed Ordering if unsupported")
> 
> from the net tree and commit:
> 
>   62ce94a7a5a5 ("PCI: Mark Broadcom HT2100 Root Port Extended Tags as broken")
> 
> from the pci tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc drivers/pci/probe.c
> index e6a917b4acd3,d11fede6bd53..000000000000
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@@ -1751,67 -1753,51 +1753,94 @@@ int pci_configure_extended_tags(struct 
>   	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;
> + 
> + 	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 (dev_cap & PCI_EXP_DEVCAP_EXT_TAG)
> + 	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;
>   }
>   
>  +/**
>  + * pcie_relaxed_ordering_enabled - Probe for PCIe relaxed ordering enable
>  + * @dev: PCI device to query
>  + *
>  + * Returns true if the device has enabled relaxed ordering attribute.
>  + */
>  +bool pcie_relaxed_ordering_enabled(struct pci_dev *dev)
>  +{
>  +	u16 v;
>  +
>  +	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &v);
>  +
>  +	return !!(v & PCI_EXP_DEVCTL_RELAX_EN);
>  +}
>  +EXPORT_SYMBOL(pcie_relaxed_ordering_enabled);
>  +
>  +static void pci_configure_relaxed_ordering(struct pci_dev *dev)
>  +{
>  +	struct pci_dev *root;
>  +
>  +	/* PCI_EXP_DEVICE_RELAX_EN is RsvdP in VFs */
>  +	if (dev->is_virtfn)
>  +		return;
>  +
>  +	if (!pcie_relaxed_ordering_enabled(dev))
>  +		return;
>  +
>  +	/*
>  +	 * For now, we only deal with Relaxed Ordering issues with Root
>  +	 * Ports. Peer-to-Peer DMA is another can of worms.
>  +	 */
>  +	root = pci_find_pcie_root_port(dev);
>  +	if (!root)
>  +		return;
>  +
>  +	if (root->dev_flags & PCI_DEV_FLAGS_NO_RELAXED_ORDERING) {
>  +		pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
>  +					   PCI_EXP_DEVCTL_RELAX_EN);
>  +		dev_info(&dev->dev, "Disable Relaxed Ordering because the Root Port didn't support it\n");
>  +	}
>  +}
>  +
>   static void pci_configure_device(struct pci_dev *dev)
>   {
>   	struct hotplug_params hpp;
>   	int ret;
>   
>   	pci_configure_mps(dev);
> - 	pci_configure_extended_tags(dev);
> + 	pci_configure_extended_tags(dev, NULL);
>  +	pci_configure_relaxed_ordering(dev);
>   
>   	memset(&hpp, 0, sizeof(hpp));
>   	ret = pci_get_hp_params(dev, &hpp);

Just a reminder that this conflict still exists.

-- 
Cheers,
Stephen Rothwell