From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: RFC: (re-)binding the VFIO platform driver to a platform device Date: Wed, 9 Oct 2013 14:21:47 -0500 Message-ID: <1381346507.7979.334.camel@snotra.buserror.net> References: <1380738758.12932.43.camel@snotra.buserror.net> <20131002184330.GC5108@cbox> <20131002203735.GA10871@kroah.com> <1380748121.12932.89.camel@snotra.buserror.net> <20131002211631.GA11914@kroah.com> <1380749715.12932.109.camel@snotra.buserror.net> <20131002234009.GA27714@kroah.com> <1380825207.12932.151.camel@snotra.buserror.net> <20131003185434.GA26123@kroah.com> <1380827494.12932.161.camel@snotra.buserror.net> <20131003203226.GB27336@kroah.com> <9F6FE96B71CF29479FF1CDC8046E15036DDA62@039-SN1MPN1-002.039d.mgd.msft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Wood Scott-B07421 , Kim Phillips , Christoffer Dall , Alex Williamson , "linux-kernel@vger.kernel.org" , "a.motakis@virtualopensystems.com" , "agraf@suse.de" , Sethi Varun-B16395 , Bhushan Bharat-R65777 , "peter.maydell@linaro.org" , "santosh.shukla@linaro.org" , "kvm@vger.kernel.org" , "gregkh@linuxfoundation.org" To: Yoder Stuart-B08248 Return-path: In-Reply-To: <9F6FE96B71CF29479FF1CDC8046E15036DDA62@039-SN1MPN1-002.039d.mgd.msft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Wed, 2013-10-09 at 14:02 -0500, Yoder Stuart-B08248 wrote: > Have been thinking about this issue some more. As Scott mentioned, > 'wildcard' matching for a driver can be fairly done in the platform > bus driver. We could add a new flag to the platform driver struct: > > diff --git a/drivers/base/platform.c b/drivers/base/platform.c > index 4f8bef3..4d6cf14 100644 > --- a/drivers/base/platform.c > +++ b/drivers/base/platform.c > @@ -727,6 +727,10 @@ static int platform_match(struct device *dev, struct device_driver *drv) > struct platform_device *pdev = to_platform_device(dev); > struct platform_driver *pdrv = to_platform_driver(drv); > > + /* the driver matches any device */ > + if (pdrv->match_any) > + return 1; > + > /* Attempt an OF style match first */ > if (of_driver_match_device(dev, drv)) > return 1; > > However, the more problematic issue is that a bus driver has no way to > differentiate from an explicit bind request via sysfs and a bind that > happened through bus probing. Again, I think the wildcard match should be orthogonal to "don't bind by default" as far as the mechanism goes. There's already a "bool suppress_bind_attrs" to prevent sysfs bind/unbind. I suggested a similar flag to mean the oppsosite -- bind *only* through sysfs. Greg KH was skeptical and wanted to see a patch before any further discussion. > diff --git a/drivers/base/base.h b/drivers/base/base.h > index 2cbc677..7a15ef3 100644 > --- a/drivers/base/base.h > +++ b/drivers/base/base.h > @@ -114,9 +114,9 @@ extern void driver_detach(struct device_driver *drv); > extern int driver_probe_device(struct device_driver *drv, struct device *dev); > extern void driver_deferred_probe_del(struct device *dev); > static inline int driver_match_device(struct device_driver *drv, > - struct device *dev) > + struct device *dev, int explicit_bind) > { > - return drv->bus->match ? drv->bus->match(dev, drv) : 1; > + return drv->bus->match ? drv->bus->match(dev, drv, explicit_bind) : 1; > } > > Of, course the above change would need to be propagated to the different > bus drivers that implement the 'match' function. ...which would not be a problem with my approach, because you could handle it in the callers of driver_match_device(). -Scott