Date:   Mon, 15 Nov 2021 05:20:17 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Lu Baolu <baolu.lu@linux.intel.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Ashok Raj <ashok.raj@intel.com>, kvm@vger.kernel.org,
        rafael@kernel.org, linux-pci@vger.kernel.org,
        Cornelia Huck <cohuck@redhat.com>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        Alex Williamson <alex.williamson@redhat.com>,
        Jacob jun Pan <jacob.jun.pan@intel.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Diana Craciun <diana.craciun@oss.nxp.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Will Deacon <will@kernel.org>
Subject: Re: [PATCH 02/11] driver core: Set DMA ownership during driver
 bind/unbind
Message-ID: <YZJekd9tdz8cLAz+@infradead.org>
References: <20211115020552.2378167-1-baolu.lu@linux.intel.com>
 <20211115020552.2378167-3-baolu.lu@linux.intel.com>
 <YZIFPv7BpsTibxE/@kroah.com>
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Precedence: bulk

On Mon, Nov 15, 2021 at 07:59:10AM +0100, Greg Kroah-Hartman wrote:
> This feels wrong to be doing it in the driver core, why doesn't the bus
> that cares about this handle it instead?
> 
> You just caused all drivers in the kernel today to set and release this
> ownership, as none set this flag.  Shouldn't it be the other way around?
> 
> And again, why not in the bus that cares?
> 
> You only have problems with 1 driver out of thousands, this feels wrong
> to abuse the driver core this way for just that one.

This isn't really a bus thingy, but related to the IOMMU subsystem.
That being said as pointed out in my previous reply I'd expect this
to go along with other IOMMU setup.