Re: [GIT PULL] Staging/IIO driver patches for 4.19-rc1

[Ahmed S. Darwish]

[ re-send; forgotten lkml CC added; sorry ]

Hi,

On Sat, 18 Aug 2018 17:57:24 +0200, Greg KH wrote:
[...]
> addition of some new IIO drivers.  Also added was a "gasket" driver from
> Google that needs loads of work and the erofs filesystem.
> 

Why are we adding __a whole new in-kernel framework__ for
developing basic user-space drivers?

We already have a frameowrk for that, and it's UIO. [1] The UIO
code is a very stable and simple subsystem; it's also heavily used
in the embedded industry..

I've looked at the gasket documentation [2], and the first user
of this new in-kernel API [3], and this is almost replicating UIO
it's not funny. [4] True, the gasket APIs adds some extra new
conveniences (PCI BAR re-mapping, MSI, ..), but there's no
technical reason this cannot be added to the UIO code instead.

More-over, the exposed user-space API is just some ioctls. So if
google hase some shipped user-space code that is using this,
hopefully the driver can still be re-implemented through UIO
without changing these bits..

Thanks,

[1] https://www.kernel.org/doc/html/v4.18/driver-api/uio-howto.html
[2] drivers/staging/gasket/gasket_core.h :: struct gasket_driver_desc
[3] drivers/staging/gasket/apex_driver.c
[4] include/linux/uio_driver.h

--
Darwi
http://darwish.chasingpointers.com