Re: [PATCH v2 1/6] Add ancillary bus support

From: Leon Romanovsky <leon@kernel.org>
To: "Ertman, David M" <david.m.ertman@intel.com>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	Parav Pandit <parav@nvidia.com>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
	"parav@mellanox.com" <parav@mellanox.com>,
	"tiwai@suse.de" <tiwai@suse.de>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"ranjani.sridharan@linux.intel.com" 
	<ranjani.sridharan@linux.intel.com>,
	"fred.oh@linux.intel.com" <fred.oh@linux.intel.com>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"dledford@redhat.com" <dledford@redhat.com>,
	"broonie@kernel.org" <broonie@kernel.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"Saleem, Shiraz" <shiraz.saleem@intel.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"Patil, Kiran" <kiran.patil@intel.com>
Subject: Re: [PATCH v2 1/6] Add ancillary bus support
Date: Thu, 8 Oct 2020 20:21:15 +0300	[thread overview]
Message-ID: <20201008172115.GP13580@unreal> (raw)
In-Reply-To: <DM6PR11MB284123995577294BE3E0C36EDD0B0@DM6PR11MB2841.namprd11.prod.outlook.com>

On Thu, Oct 08, 2020 at 04:42:48PM +0000, Ertman, David M wrote:
> > -----Original Message-----
> > From: Leon Romanovsky <leon@kernel.org>
> > Sent: Thursday, October 8, 2020 1:00 AM
> > To: Williams, Dan J <dan.j.williams@intel.com>
> > Cc: Ertman, David M <david.m.ertman@intel.com>; Parav Pandit
> > <parav@nvidia.com>; Pierre-Louis Bossart <pierre-
> > louis.bossart@linux.intel.com>; alsa-devel@alsa-project.org;
> > parav@mellanox.com; tiwai@suse.de; netdev@vger.kernel.org;
> > ranjani.sridharan@linux.intel.com; fred.oh@linux.intel.com; linux-
> > rdma@vger.kernel.org; dledford@redhat.com; broonie@kernel.org; Jason
> > Gunthorpe <jgg@nvidia.com>; gregkh@linuxfoundation.org;
> > kuba@kernel.org; Saleem, Shiraz <shiraz.saleem@intel.com>;
> > davem@davemloft.net; Patil, Kiran <kiran.patil@intel.com>
> > Subject: Re: [PATCH v2 1/6] Add ancillary bus support
> >
> > On Thu, Oct 08, 2020 at 12:38:00AM -0700, Dan Williams wrote:
> > > On Thu, Oct 8, 2020 at 12:01 AM Leon Romanovsky <leon@kernel.org>
> > wrote:
> > > [..]
> > > > All stated above is my opinion, it can be different from yours.
> > >
> > > Yes, but we need to converge to move this forward. Jason was involved
> > > in the current organization for registration, Greg was angling for
> > > this to be core functionality. I have use cases outside of RDMA and
> > > netdev. Parav was ok with the current organization. The SOF folks
> > > already have a proposed incorporation of it. The argument I am hearing
> > > is that "this registration api seems hard for driver writers" when we
> > > have several driver writers who have already taken a look and can make
> > > it work. If you want to follow on with a simpler wrappers for your use
> > > case, great, but I do not yet see anyone concurring with your opinion
> > > that the current organization is irretrievably broken or too obscure
> > > to use.
> >
> > Can it be that I'm first one to use this bus for very large driver (>120K LOC)
> > that has 5 different ->probe() flows?
> >
> > For example, this https://lore.kernel.org/linux-
> > rdma/20201006172317.GN1874917@unreal/
> > hints to me that this bus wasn't used with anything complex as it was initially
> > intended.
> >
> > And regarding registration, I said many times that init()/add() scheme is ok,
> > the inability
> > to call to uninit() after add() failure is not ok from my point of view.
>
> So, to address your concern of not being able to call an uninit after a add failure
> I can break the unregister flow into two steps also.  An uninit and a delete to mirror
> the registration process's init and add.
>
> Would this make the registration and un-registration flow acceptable?

Yes, sure.

>
> -DaveE
>
>
>
> >
> > Thanks