Re: RFC: (re-)binding the VFIO platform driver to a platform device

From: Greg Kroah-Hartman
Date: Tue Oct 01 2013 - 16:01:11 EST


On Tue, Oct 01, 2013 at 01:38:31PM -0500, Kim Phillips wrote:
> Hi,
>
> Santosh and I are having a problem figuring out how to enable binding
> (and re-binding) platform devices to a platform VFIO driver (see
> Antonis' WIP: [1]) in an upstream-acceptable manner.
>
> Binding platform drivers currently depends on a string match in the
> device node's compatible entry. On an arndale, one can currently
> rebind the same device to the same driver like so:
>
> echo 12ce0000.i2c > /sys/bus/platform/drivers/s3c-i2c/12ce0000.i2c/driver/unbind
> echo 12ce0000.i2c > /sys/bus/platform/drivers/s3c-i2c/bind
>
> And one can bind it to the vfio-dt driver, as Antonis instructs, by
> appending a 'vfio-dt' string to the device tree compatible entry for
> the device. Then this would work:
>
> echo 12ce0000.i2c > /sys/bus/platform/drivers/s3c-i2c/12ce0000.i2c/driver/unbind
> echo 12ce0000.i2c > /sys/bus/platform/drivers/vfio-dt/bind
>
> Consequently, the hack patch below [2] allows any platform device to be
> bound to the vfio-dt driver, without making changes to the device
> tree. It's a hack because I don't see having any driver name specific
> code in drivers/base/bus.c being upstream acceptable.

You are correct.

What is wrong with just doing the above unbind/bind things through
sysfs, that is what it is there for, right?

greg k-h
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