Re: [PATCH v1 6/8] gpu/host1x: Use iommu_attach/detach_device()

[Lu Baolu]

On 1/6/22 11:35 PM, Jason Gunthorpe wrote:
> On Thu, Jan 06, 2022 at 10:20:51AM +0800, Lu Baolu wrote:
> > Ordinary drivers should use iommu_attach/detach_device() for domain
> > attaching and detaching.
> >
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> >   drivers/gpu/host1x/dev.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
> > index fbb6447b8659..6e08cb6202cc 100644
> > +++ b/drivers/gpu/host1x/dev.c
> > @@ -265,7 +265,7 @@ static struct iommu_domain *host1x_iommu_attach(struct host1x *host)
> >   			goto put_cache;
> >   		}
> >   
> > -		err = iommu_attach_group(host->domain, host->group);
> > +		err = iommu_attach_device(host->domain, host->dev);
> >   		if (err) {
> >   			if (err == -ENODEV)
> >   				err = 0;
> > @@ -335,7 +335,7 @@ static void host1x_iommu_exit(struct host1x *host)
> >   {
> >   	if (host->domain) {
> >   		put_iova_domain(&host->iova);
> > -		iommu_detach_group(host->domain, host->group);
> > +		iommu_detach_device(host->domain, host->dev);
> >   
> >   		iommu_domain_free(host->domain);
> >   		host->domain = NULL;
>
> Shouldn't this add the flag to tegra_host1x_driver ?

This is called for a single driver. The call trace looks like below:

static struct platform_driver tegra_host1x_driver = {
        .driver = {
                .name = "tegra-host1x",
                .of_match_table = host1x_of_match,
        },
        .probe = host1x_probe,
        .remove = host1x_remove,
};

host1x_probe(dev)
->host1x_iommu_init(host)	//host is a wrapper of dev
-->host1x_iommu_attach(host)
---->iommu_group_get(host->dev)
     iommu_domain_alloc(&platform_bus_type)
     iommu_attach_group(domain, group);

It seems that the existing code only works for singleton group.

> And do like we did in the other tegra stuff and switch to the dma api
> when !host1x_wants_iommu() ?
>
> Jason

Best regards,
baolu