linux-kernel - Re: [RFC PATCH v2 06/27] PCI: endpoint: pci-epf-vntb: Use pci_epc_map

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Message-ID: <aS3tr2QVElXII3vX@lizhi-Precision-Tower-5810>
Date: Mon, 1 Dec 2025 14:34:07 -0500
From: Frank Li <Frank.li@....com>
To: Koichiro Den <den@...inux.co.jp>
Cc: ntb@...ts.linux.dev, linux-pci@...r.kernel.org,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	mani@...nel.org, kwilczynski@...nel.org, kishon@...nel.org,
	bhelgaas@...gle.com, corbet@....net, vkoul@...nel.org,
	jdmason@...zu.us, dave.jiang@...el.com, allenbh@...il.com,
	Basavaraj.Natikar@....com, Shyam-sundar.S-k@....com,
	kurt.schwemmer@...rosemi.com, logang@...tatee.com,
	jingoohan1@...il.com, lpieralisi@...nel.org, robh@...nel.org,
	jbrunet@...libre.com, fancer.lancer@...il.com, arnd@...db.de,
	pstanner@...hat.com, elfring@...rs.sourceforge.net
Subject: Re: [RFC PATCH v2 06/27] PCI: endpoint: pci-epf-vntb: Use
 pci_epc_map_inbound() for MW mapping

On Sun, Nov 30, 2025 at 01:03:44AM +0900, Koichiro Den wrote:
> Switch MW setup to use pci_epc_map_inbound() when supported. This allows
> mapping portions of a BAR rather than the entire region, supporting
> partial BAR usage on capable controllers.
>
> Signed-off-by: Koichiro Den <den@...inux.co.jp>
> ---
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 21 ++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 1ff414703566..42e57721dcb4 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -728,10 +728,15 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
>  				PCI_BASE_ADDRESS_MEM_TYPE_64 :
>  				PCI_BASE_ADDRESS_MEM_TYPE_32;
>
> -		ret = pci_epc_set_bar(ntb->epf->epc,
> -				      ntb->epf->func_no,
> -				      ntb->epf->vfunc_no,
> -				      &ntb->epf->bar[barno]);
> +		ret = pci_epc_map_inbound(ntb->epf->epc,
> +					  ntb->epf->func_no,
> +					  ntb->epf->vfunc_no,
> +					  &ntb->epf->bar[barno], 0);
> +		if (ret == -EOPNOTSUPP)
> +			ret = pci_epc_set_bar(ntb->epf->epc,
> +					      ntb->epf->func_no,
> +					      ntb->epf->vfunc_no,
> +					      &ntb->epf->bar[barno]);
>  		if (ret) {
>  			dev_err(dev, "MW set failed\n");
>  			goto err_set_bar;
> @@ -1385,17 +1390,23 @@ static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
>  	struct epf_ntb *ntb = ntb_ndev(ndev);
>  	struct pci_epf_bar *epf_bar;
>  	enum pci_barno barno;
> +	struct pci_epc *epc;
>  	int ret;
>  	struct device *dev;
>
> +	epc = ntb->epf->epc;
>  	dev = &ntb->ntb.dev;
>  	barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
> +

Nit: unnecesary change here

Reviewed-by: Frank Li <Frank.Li@....com>

>  	epf_bar = &ntb->epf->bar[barno];
>  	epf_bar->phys_addr = addr;
>  	epf_bar->barno = barno;
>  	epf_bar->size = size;
>
> -	ret = pci_epc_set_bar(ntb->epf->epc, 0, 0, epf_bar);
> +	ret = pci_epc_map_inbound(epc, 0, 0, epf_bar, 0);
> +	if (ret == -EOPNOTSUPP)
> +		ret = pci_epc_set_bar(epc, 0, 0, epf_bar);
> +
>  	if (ret) {
>  		dev_err(dev, "failure set mw trans\n");
>  		return ret;
> --
> 2.48.1
>