On 2021/3/19 13:40, Viresh Kumar wrote:
On 19-03-21, 13:31, Jie Deng wrote:
On 2021/3/19 11:54, Viresh Kumar wrote:
On 18-03-21, 15:52, Arnd Bergmann wrote:
Allowing multiple virtio-i2c controllers in one system, and multiple i2c
devices attached to each controller is clearly something that has to work.
Good.
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.
+ .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.
I also see example drivers/i2c/busses/i2c-xiic.c. Some people might
think this way is more clearer than
updating each member in probe. Basically, I think it's just a matter of
personal preference which doesn't
solve any problems.
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