Re: [PATCH] drm/tegra: Remove of_dma_configure() from host1x_device_add()

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Feb 02, 2024 at 03:56:52PM +0000, Jon Hunter wrote:
> 
> On 02/02/2024 14:35, Jason Gunthorpe wrote:
> > On Fri, Feb 02, 2024 at 10:40:36AM +0000, Jon Hunter wrote:
> > 
> > > > But, what is the actual log output you see, is it -EEXIST?
> > > 
> > > I see ...
> > > 
> > >   ERR KERN host1x drm: iommu configuration for device failed with -ENOENT
> > 
> > So that shouldn't happen in you case as far as I can tell, the device
> > is properly added, link->kobj should be fine and ENOENT shouldn't
> > happen.
> > 
> > > > If it is coming and going is it a race of some kind?
> > > 
> > > It is consistent without the above. However, I did not think that the
> > > above change would change the returning on -ENOENT? I will add more
> > > debug.
> > 
> > I do not think it can either
> > 
> > Still wonder if there is some odd race..
> > 
> > Let me know when you figure out what is happening - I think there is
> > some bug here it is not just a harmless warning.
> 
> 
> Yes looks like a race of some sort. Adding a bit of debug also makes the
> issue go away so difficult to see what is happening.

I'm wondering if it is racing with iommu driver probing? I looked but
didn't notice anything obviously wrong there that would cause this
though.

Though, it shouldn't be racing with self-removal of the device it just
added, that would be crazy???

Jason