On 19-03-21, 13:31, Jie Deng wrote:

On 2021/3/19 11:54, Viresh Kumar wrote:

quoted

On 18-03-21, 15:52, Arnd Bergmann wrote:

quoted

Allowing multiple virtio-i2c controllers in one system, and multiple i2c
devices attached to each controller is clearly something that has to work.

Good.

quoted

I don't actually see a limitation though. Viresh, what is the problem
you see for having multiple controllers?

I thought this would be a problem in that case as we are using the global
virtio_adapter here.

+       vi->adap = &virtio_adapter;
+       i2c_set_adapdata(vi->adap, vi);

Multiple calls to probe() will end up updating the same pointer inside adap.

+       vi->adap->dev.parent = &vdev->dev;

Same here, overwrite.

+       /* Setup ACPI node for controlled devices which will be probed through ACPI */
+       ACPI_COMPANION_SET(&vi->adap->dev, ACPI_COMPANION(pdev));
+       vi->adap->timeout = HZ / 10;

These may be fine, but still not ideal I believe.

+       ret = i2c_add_adapter(vi->adap);
i
This should be a problem as well, we must be adding this to some sort of list,
doing some RPM stuff, etc ?

Jie, the solution is to allocate memory for adap at runtime in probe and remove
the virtio_adapter structure completely.

If you want to support that. Then I think we don't need to change the
following at all.

quoted

+    .algo = &virtio_algorithm,
+
+        return ret;
+
+    vi->adap = virtio_adapter;

This is strange, why are you allocating memory for adapter twice ?
Once for virtio_adapter and once for vi->adap ? Either fill the fields
directly for v->adap here and remove virtio_adapter or make vi->adap a
pointer.

Yes, your previous version was partly okay but you don't need the
virtio_algorithm structure to be allocated. There are only 4 fields you are
updating here, just fill them directly in vi->adap.

(FWIW, I also suggested the same when I said
"Either fill the fields directly for v->adap here and remove virtio_adapter".
)

See how drivers/i2c/busses/i2c-versatile.c and most of the other drivers have
done it.

-- 
viresh