netdev - Re: [PATCH V7 5/9] PCI/IOV: Enable 10-Bit tag support for PCIe VF devices

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Date:   Wed, 4 Aug 2021 18:29:37 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Dongdong Liu <liudongdong3@...wei.com>
Cc:     hch@...radead.org, kw@...ux.com, logang@...tatee.com,
        leon@...nel.org, linux-pci@...r.kernel.org, rajur@...lsio.com,
        hverkuil-cisco@...all.nl, linux-media@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH V7 5/9] PCI/IOV: Enable 10-Bit tag support for PCIe VF
 devices

On Wed, Aug 04, 2021 at 09:47:04PM +0800, Dongdong Liu wrote:
> Enable VF 10-Bit Tag Requester when it's upstream component support
> 10-bit Tag Completer.

s/it's/its/
s/support/supports/

I think "upstream component" here means the PF, doesn't it?  I don't
think the PF is really an *upstream* component; there's no routing
like with a switch.

> Signed-off-by: Dongdong Liu <liudongdong3@...wei.com>
> Reviewed-by: Christoph Hellwig <hch@....de>
> ---
>  drivers/pci/iov.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index dafdc65..0d0bed1 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -634,6 +634,10 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>  
>  	pci_iov_set_numvfs(dev, nr_virtfn);
>  	iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE;
> +	if ((iov->cap & PCI_SRIOV_CAP_VF_10BIT_TAG_REQ) &&
> +	    dev->ext_10bit_tag)
> +		iov->ctrl |= PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN;
> +
>  	pci_cfg_access_lock(dev);
>  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
>  	msleep(100);
> @@ -650,6 +654,8 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>  
>  err_pcibios:
>  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
> +	if (iov->ctrl & PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN)
> +		iov->ctrl &= ~PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN;
>  	pci_cfg_access_lock(dev);
>  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
>  	ssleep(1);
> @@ -682,6 +688,8 @@ static void sriov_disable(struct pci_dev *dev)
>  
>  	sriov_del_vfs(dev);
>  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
> +	if (iov->ctrl & PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN)
> +		iov->ctrl &= ~PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN;

You can just clear PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN unconditionally,
can't you?  I know it wouldn't change anything, but removing the "if"
makes the code prettier.  You could just add it in the existing
PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE mask.

>  	pci_cfg_access_lock(dev);
>  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
>  	ssleep(1);
> -- 
> 2.7.4
>