linux-kernel - Re: [RFC PATCH 8/9] PCI/PME: Add RCEC PME handling

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Message-ID: <20200804104713.0000767f@Huawei.com>
Date:   Tue, 4 Aug 2020 10:47:13 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Jay Fang <f.fangjian@...wei.com>
CC:     Sean V Kelley <sean.v.kelley@...el.com>, <bhelgaas@...gle.com>,
        <rjw@...ysocki.net>, <ashok.raj@...nel.org>, <tony.luck@...el.com>,
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Qiuxu Zhuo <qiuxu.zhuo@...el.com>
Subject: Re: [RFC PATCH 8/9] PCI/PME: Add RCEC PME handling

On Tue, 4 Aug 2020 16:35:59 +0800
Jay Fang <f.fangjian@...wei.com> wrote:

> 在 2020/7/25 1:22, Sean V Kelley 写道:
> > The Root Complex Event Collectors(RCEC) appear as peers of Root Ports
> > and also have the PME capability. So add RCEC support to the current PME
> > service driver and attach the PME service driver to the RCEC device.
> > 
> > Co-developed-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> > Signed-off-by: Sean V Kelley <sean.v.kelley@...el.com>
> > Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> > ---
> >  drivers/pci/pcie/pme.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c
> > index 6a32970bb731..87799166c96a 100644
> > --- a/drivers/pci/pcie/pme.c
> > +++ b/drivers/pci/pcie/pme.c
> > @@ -310,7 +310,10 @@ static int pcie_pme_can_wakeup(struct pci_dev *dev, void *ign)
> >  static void pcie_pme_mark_devices(struct pci_dev *port)
> >  {
> >  	pcie_pme_can_wakeup(port, NULL);
> > -	if (port->subordinate)
> > +
> > +	if (pci_pcie_type(port) == PCI_EXP_TYPE_RC_EC)
> > +		pcie_walk_rcec(port, pcie_pme_can_wakeup, NULL);
> > +	else if (port->subordinate)
> >  		pci_walk_bus(port->subordinate, pcie_pme_can_wakeup, NULL);
> >  }
> >  
> > @@ -320,10 +323,15 @@ static void pcie_pme_mark_devices(struct pci_dev *port)
> >   */
> >  static int pcie_pme_probe(struct pcie_device *srv)
> >  {
> > -	struct pci_dev *port;
> > +	struct pci_dev *port = srv->port;
> >  	struct pcie_pme_service_data *data;
> >  	int ret;
> >  
> > +	/* Limit to Root Ports or Root Complex Event Collectors */
> > +	if ((pci_pcie_type(port) != PCI_EXP_TYPE_RC_EC) &&
> > +	    (pci_pcie_type(port) != PCI_EXP_TYPE_ROOT_PORT))
> > +		return -ENODEV;
> > +
> >  	data = kzalloc(sizeof(*data), GFP_KERNEL);
> >  	if (!data)
> >  		return -ENOMEM;
> > @@ -333,7 +341,6 @@ static int pcie_pme_probe(struct pcie_device *srv)
> >  	data->srv = srv;
> >  	set_service_data(srv, data);
> >  
> > -	port = srv->port;
> >  	pcie_pme_interrupt_enable(port, false);
> >  	pcie_clear_root_pme_status(port);
> >  
> > @@ -445,7 +452,7 @@ static void pcie_pme_remove(struct pcie_device *srv)
> >  
> >  static struct pcie_port_service_driver pcie_pme_driver = {
> >  	.name		= "pcie_pme",
> > -	.port_type	= PCI_EXP_TYPE_ROOT_PORT,
> > +	.port_type	= PCIE_ANY_PORT,  
> Maybe we can use port_type for driver matching. There is no need
> to check the type of port in pcie_pme_probe function.
> 

I walked into the same hole for the AER case.  
port_type is effectively an enum so there is no way of specifying several
types unless you want to register different instances of pcie_port_service_driver
and that isn't currently possible.

The PCIE_ANY_PORT is a special case value.

https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/pci_regs.h#L477
https://elixir.bootlin.com/linux/latest/source/drivers/pci/pci-driver.c#L1651

So odd corner case, but I think this is the right solution. Anything better
would require a lot more code to change.

Jonathan





> 
> Jay
> 
> >  	.service	= PCIE_PORT_SERVICE_PME,
> >  
> >  	.probe		= pcie_pme_probe,
> >