From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:23142 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726010AbfFUNhq (ORCPT ); Fri, 21 Jun 2019 09:37:46 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5LDba15099061 for ; Fri, 21 Jun 2019 09:37:45 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2t8y882wrw-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 21 Jun 2019 09:37:41 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 21 Jun 2019 14:37:17 +0100 Date: Fri, 21 Jun 2019 15:37:11 +0200 From: Halil Pasic Subject: Re: [PATCH] s390/cio: introduce driver_override on the css bus In-Reply-To: <20190621115604.0f3e3f69.cohuck@redhat.com> References: <20190613110815.17251-1-cohuck@redhat.com> <20190621115604.0f3e3f69.cohuck@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Message-Id: <20190621153711.7d713c4d.pasic@linux.ibm.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Cornelia Huck Cc: Sebastian Ott , Peter Oberparleiter , Alex Williamson , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org On Fri, 21 Jun 2019 11:56:04 +0200 Cornelia Huck wrote: > On Thu, 13 Jun 2019 13:08:15 +0200 > Cornelia Huck wrote: > > > Sometimes, we want to control which of the matching drivers > > binds to a subchannel device (e.g. for subchannels we want to > > handle via vfio-ccw). > > > > For pci devices, a mechanism to do so has been introduced in > > 782a985d7af2 ("PCI: Introduce new device binding path using > > pci_dev.driver_override"). It makes sense to introduce the > > driver_override attribute for subchannel devices as well, so > > that we can easily extend the 'driverctl' tool (which makes > > use of the driver_override attribute for pci). > > > > Note that unlike pci we still require a driver override to > > match the subchannel type; matching more than one subchannel > > type is probably not useful anyway. > > > > Signed-off-by: Cornelia Huck Reviewed-by: Halil Pasic I guess the '\n' handling is customary, and is what the same what the pci counterpart (782a985d7af2) does anyway. It bothers me a little that you don't necessarily get back from with show what you stored. E.g. # echo -e "bug\nfree" > /sys/bus/css/devices/0.0.0001/driver_override # echo $? 0 # cat /sys/bus/css/devices/0.0.0001/driver_override bug # echo $? 0 But given the previous art (782a985d7af2) I think it is the best way to do it. The rest is very straightforward. > > --- > > > > Lightly tested; did not yet attempt to adapt driverctl to actually > > make use of it. > > Friendly ping. > > In the meanwhile, I figured out that you do not need to adapt driverctl > at all, but just need to pass it '-b css' to work on the css bus; this > seems to work just fine with this patch applied. > Interesting. I hope to get around and have a closer look at it eventually. Regards, Halil