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

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Message-ID: <yvxxbc4jaury7i5x4qewgajra65y3gulmvuuxqktoozbcoy3pl@k46gz22j24zc>
Date: Tue, 2 Dec 2025 15:26:50 +0900
From: Koichiro Den <den@...inux.co.jp>
To: Frank Li <Frank.li@....com>
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 Mon, Dec 01, 2025 at 02:34:07PM -0500, Frank Li wrote:
> 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

I'll drop it in the next iteration. Thanks,

Koichiro

> 
> 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
> >