linux-kernel - Re: [PATCH] PCI: endpoint: Don't stop EP controller by EP function

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Message-ID: <20220706202514.GA218769@bhelgaas>
Date:   Wed, 6 Jul 2022 15:25:14 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Shunsuke Mie <mie@...l.co.jp>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Hou Zhiqiang <Zhiqiang.Hou@....com>,
        Li Chen <lchen@...arella.com>, linux-pci@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: endpoint: Don't stop EP controller by EP function

On Wed, Jul 06, 2022 at 12:15:38PM +0900, Shunsuke Mie wrote:
> 2022年7月6日(水) 12:08 Bjorn Helgaas <helgaas@...nel.org>:
> > On Wed, Jul 06, 2022 at 11:37:29AM +0900, Shunsuke Mie wrote:
> > > 2022年7月6日(水) 7:40 Bjorn Helgaas <helgaas@...nel.org>:
> > > > On Wed, Jun 22, 2022 at 01:09:24PM +0900, Shunsuke Mie wrote:
> > > > > For multi-function endpoint device, an ep function shouldn't stop EP
> > > > > controller. Nomally the controller is stopped via configfs.
> > > >
> > > > Can you please clarify this for me?
> > > >
> > > > An endpoint function by itself wouldn't stop an endpoint controller.
> > > > I assume that some *operation* on an endpoint function currently stops
> > > > the endpoint controller, but that operation should not stop the
> > > > controller?
> > > >
> > > > I guess the operation is an "unbind" that detaches an EPF device from
> > > > an EPC device?
> > >
> > > It is likely that after all of the endpoint functions are unbound, the
> > > controller can be stopped safely, but I'm not sure if it is desired behavior
> > > for endpoint framework.
> >
> > I'm not asking about the patch itself.  I'm asking about the commit
> > log because "an EP function shouldn't stop EP controller" doesn't
> > quite make sense in English.
> I'm sorry.
> 
> > I suspect it should say something like "unbinding one endpoint
> > function of a multi-function device from the endpoint controller
> > should not stop the controller."
> Yes, it is correct and represents the commit clearly.

Thanks!  I updated the commit log to the following:

  PCI: endpoint: Don't stop controller when unbinding endpoint function

  Unbinding an endpoint function from the endpoint controller shouldn't stop
  the controller.  This is especially a problem for multi-function endpoints
  where other endpoints may still be active.

  Don't stop the controller when unbinding one of its endpoints.  Normally
  the controller is stopped via configfs.