Re: [PATCH v3 04/18] driver core: platform: Add driver dma ownership management

From: Jason Gunthorpe <jgg@nvidia.com>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Joerg Roedel <joro@8bytes.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Dan Williams <dan.j.williams@intel.com>,
	rafael@kernel.org, Diana Craciun <diana.craciun@oss.nxp.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Eric Auger <eric.auger@redhat.com>, Liu Yi L <yi.l.liu@intel.com>,
	Jacob jun Pan <jacob.jun.pan@intel.com>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Stuart Yoder <stuyoder@gmail.com>,
	Laurentiu Tudor <laurentiu.tudor@nxp.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Li Yang <leoyang.li@nxp.com>, Dmitry Osipenko <digetx@gmail.com>,
	iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 04/18] driver core: platform: Add driver dma ownership management
Date: Tue, 7 Dec 2021 09:16:27 -0400	[thread overview]
Message-ID: <20211207131627.GA6385@nvidia.com> (raw)
In-Reply-To: <56a63776-48ca-0d6e-c25c-016dc016e0d5@linux.intel.com>

On Tue, Dec 07, 2021 at 10:57:25AM +0800, Lu Baolu wrote:
> On 12/6/21 11:06 PM, Jason Gunthorpe wrote:
> > On Mon, Dec 06, 2021 at 06:36:27AM -0800, Christoph Hellwig wrote:
> > > I really hate the amount of boilerplate code that having this in each
> > > bus type causes.
> > +1
> > 
> > I liked the first version of this series better with the code near
> > really_probe().
> > 
> > Can we go back to that with some device_configure_dma() wrapper
> > condtionally called by really_probe as we discussed?
> > 
> 
> Are you talking about below change?
> 
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 68ea1f949daa..368f9e530515 100644
> +++ b/drivers/base/dd.c
> @@ -577,7 +577,13 @@ static int really_probe(struct device *dev, struct
> device_driver *drv)
>  	if (dev->bus->dma_configure) {
>  		ret = dev->bus->dma_configure(dev);
>  		if (ret)
> -			goto probe_failed;
> +			goto pinctrl_bind_failed;
> +
> +		if (!drv->no_kernel_dma) {
> +			ret = iommu_device_set_dma_owner(dev, DMA_OWNER_DMA_API, NULL);
> +			if (ret)
> +				goto pinctrl_bind_failed;
> +                }
>  	}

Yes, the suggestion was to put everything that 'if' inside a function
and then of course a matching undo function.

Jason